Change search
Refine search result
123 1 - 50 of 109
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Aad, G.
    et al.
    Åsman, Barbro
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, K. Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David A.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian C.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel B.
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zutshi, V.
    Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton Collisions with the ATLAS Detector at the LHC2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, no 16, p. 161801-Article in journal (Refereed)
    Abstract [en]

    A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315 nb(-1) collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C. L. the q* mass interval 0: 30< m(q)*< 1:26 TeV, extending the reach of previous experiments.

  • 2. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nisa, M. U.
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmerman, M.
    Search for Extended Sources of Neutrino Emission in the Galactic Plane with IceCube2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 956, no 1, article id 20Article in journal (Refereed)
    Abstract [en]

    The Galactic plane, harboring a diffuse neutrino flux, is a particularly interesting target in which to study potential cosmic-ray acceleration sites. Recent gamma-ray observations by HAWC and LHAASO have presented evidence for multiple Galactic sources that exhibit a spatially extended morphology and have energy spectra continuing beyond 100 TeV. A fraction of such emission could be produced by interactions of accelerated hadronic cosmic rays, resulting in an excess of high-energy neutrinos clustered near these regions. Using 10 years of IceCube data comprising track-like events that originate from charged-current muon neutrino interactions, we perform a dedicated search for extended neutrino sources in the Galaxy. We find no evidence for time-integrated neutrino emission from the potential extended sources studied in the Galactic plane. The most significant location, at 2.6σ post-trials, is a sized region coincident with the unidentified TeV gamma-ray source 3HWC J1951+266. We provide strong constraints on hadronic emission from several regions in the galaxy.

  • 3. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    A Search for IceCube Sub-TeV Neutrinos Correlated with Gravitational-wave Events Detected By LIGO/Virgo2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 959, no 2, article id 96Article in journal (Refereed)
    Abstract [en]

    The LIGO/Virgo collaboration published the catalogs GWTC-1, GWTC-2.1, and GWTC-3 containing candidate gravitational-wave (GW) events detected during its runs O1, O2, and O3. These GW events can be possible sites of neutrino emission. In this paper, we present a search for neutrino counterparts of 90 GW candidates using IceCube DeepCore, the low-energy infill array of the IceCube Neutrino Observatory. The search is conducted using an unbinned maximum likelihood method, within a time window of 1000 s, and uses the spatial and timing information from the GW events. The neutrinos used for the search have energies ranging from a few GeV to several tens of TeV. We do not find any significant emission of neutrinos, and place upper limits on the flux and the isotropic-equivalent energy emitted in low-energy neutrinos. We also conduct a binomial test to search for source populations potentially contributing to neutrino emission. We report a nondetection of a significant neutrino-source population with this test.

  • 4. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm Univ, Oskar Klein Ctr, Stockholm, Sweden.
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    Constraints on Populations of Neutrino Sources from Searches in the Directions of IceCube Neutrino Alerts2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 951, no 1, article id 45Article in journal (Refereed)
    Abstract [en]

    Beginning in 2016, the IceCube Neutrino Observatory has sent out alerts in real time containing the information of high-energy (E & GSIM; 100 TeV) neutrino candidate events with moderate to high (& GSIM;30%) probability of astrophysical origin. In this work, we use a recent catalog of such alert events, which, in addition to events announced in real time, includes events that were identified retroactively and covers the time period of 2011-2020. We also search for additional, lower-energy neutrinos from the arrival directions of these IceCube alerts. We show how performing such an analysis can constrain the contribution of rare populations of cosmic neutrino sources to the diffuse astrophysical neutrino flux. After searching for neutrino emission coincident with these alert events on various timescales, we find no significant evidence of either minute-scale or day-scale transient neutrino emission or of steady neutrino emission in the direction of these alert events. This study also shows how numerous a population of neutrino sources has to be to account for the complete astrophysical neutrino flux. Assuming that sources have the same luminosity, an E (-2.5) neutrino spectrum, and number densities that follow star formation rates, the population of sources has to be more numerous than 7 x 10(-9) Mpc(-3). This number changes to 3 x 10(-7) Mpc(-3) if number densities instead have no cosmic evolution.

  • 5. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    IceCat-1: The IceCube Event Catalog of Alert Tracks2023In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 269, no 1, article id 25Article in journal (Refereed)
    Abstract [en]

    We present a catalog of likely astrophysical neutrino track-like events from the IceCube Neutrino Observatory. IceCube began reporting likely astrophysical neutrinos in 2016, and this system was updated in 2019. The catalog presented here includes events that were reported in real time since 2019, as well as events identified in archival data samples starting from 2011. We report 275 neutrino events from two selection channels as the first entries in the catalog, the IceCube Event Catalog of Alert Tracks, which will see ongoing extensions with additional alerts. The Gold and Bronze alert channels respectively provide neutrino candidates with a 50% and 30% probability of being astrophysical, on average assuming an astrophysical neutrino power-law energy spectral index of 2.19. For each neutrino alert, we provide the reconstructed energy, direction, false-alarm rate, probability of being astrophysical in origin, and likelihood contours describing the spatial uncertainty in the alert's reconstructed location. We also investigate a directional correlation of these neutrino events with gamma-ray and X-ray catalogs, including 4FGL, 3HWC, TeVCat, and Swift-BAT.

  • 6. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    Search for Correlations of High-energy Neutrinos Detected in IceCube with Radio-bright AGN and Gamma-Ray Emission from Blazars2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 954, no 1, article id 75Article in journal (Refereed)
    Abstract [en]

    The IceCube Neutrino Observatory sends realtime neutrino alerts with a high probability of being astrophysical in origin. We present a new method to correlate these events and possible candidate sources using 2089 blazars from the Fermi-LAT 4LAC-DR2 catalog and with 3413 active galactic nuclei (AGNs) from the Radio Fundamental Catalog. No statistically significant neutrino emission was found in any of the catalog searches. The result suggests that a small fraction, <1%, of the studied AGNs emit neutrinos that pass the alert criteria, and is compatible with prior evidence for neutrino emission presented by IceCube and other authors from sources such as TXS 0506 + 056 and PKS 1502 + 106. We also present cross-checks to other analyses that claim a significant correlation using similar data samples.

  • 7. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    Search for neutrino lines from dark matter annihilation and decay with IceCube2023In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, no 10, article id 102004Article in journal (Refereed)
    Abstract [en]

    Dark matter particles in the Galactic Center and halo can annihilate or decay into a pair of neutrinos producing a monochromatic flux of neutrinos. The spectral feature of this signal is unique and it is not expected from any astrophysical production mechanism. Its observation would constitute a dark matter smoking gun signal. We performed the first dedicated search with a neutrino telescope for such signal, by looking at both the angular and energy information of the neutrino events. To this end, a total of five years of IceCube’s DeepCore data has been used to test dark matter masses ranging from 10 GeV to 40 TeV. No significant neutrino excess was found and upper limits on the annihilation cross section, as well as lower limits on the dark matter lifetime, were set. The limits reached are of the order of 10−24  cm3/s for an annihilation and up to 1027  s for decaying dark matter. Using the same data sample we also derive limits for dark matter annihilation or decay into a pair of Standard Model charged particles.

     

  • 8. Abbasi, R.
    et al.
    Deoskar, Kunal
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    Search for sub-TeV Neutrino Emission from Novae with IceCube-DeepCore2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 953, no 2, article id 160Article in journal (Refereed)
    Abstract [en]

    The understanding of novae, the thermonuclear eruptions on the surfaces of white dwarf stars in binaries, has recently undergone a major paradigm shift. Though the bolometric luminosity of novae was long thought to arise directly from photons supplied by the thermonuclear runaway, recent gigaelectronvolt (GeV) gamma-ray observations have supported the notion that a significant portion of the luminosity could come from radiative shocks. More recently, observations of novae have lent evidence that these shocks are acceleration sites for hadrons for at least some types of novae. In this scenario, a flux of neutrinos may accompany the observed gamma rays. As the gamma rays from most novae have only been observed up to a few GeV, novae have previously not been considered as targets for neutrino telescopes, which are most sensitive at and above teraelectronvolt (TeV) energies. Here, we present the first search for neutrinos from novae with energies between a few GeV and 10 TeV using IceCube-DeepCore, a densely instrumented region of the IceCube Neutrino Observatory with a reduced energy threshold. We search both for a correlation between gamma-ray and neutrino emission as well as between optical and neutrino emission from novae. We find no evidence for neutrino emission from the novae considered in this analysis and set upper limits for all gamma-ray detected novae.

  • 9. Abbasi, Rasha
    et al.
    Deoskar, Kunar
    Stockholm Univ, Oskar Klein Ctr, SE-10691 Stockholm, Sweden.
    Finley, Chad
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zhelnin, P.
    Limits on Neutrino Emission from GRB 221009A from MeV to PeV Using the IceCube Neutrino Observatory2023In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 946, no 1, article id L26Article in journal (Refereed)
    Abstract [en]

    Gamma-ray bursts (GRBs) have long been considered a possible source of high-energy neutrinos. While no correlations have yet been detected between high-energy neutrinos and GRBs, the recent observation of GRB 221009A-the brightest GRB observed by Fermi-GBM to date and the first one to be observed above an energy of 10 TeV-provides a unique opportunity to test for hadronic emission. In this paper, we leverage the wide energy range of the IceCube Neutrino Observatory to search for neutrinos from GRB 221009A. We find no significant deviation from background expectation across event samples ranging from MeV to PeV energies, placing stringent upper limits on the neutrino emission from this source.

  • 10.
    Bohm, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Danared, H.
    Stockholm University, Faculty of Science, Department of Physics.
    Hedqvist, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Hellberg, Fredrik
    Stockholm University, Faculty of Science, Department of Physics.
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Robson, C.
    Stockholm University, Faculty of Science, Department of Physics.
    A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator2020In: Nature Photonics, ISSN 1749-4885, E-ISSN 1749-4893, Vol. 14, no 6, p. 391-397Article in journal (Refereed)
    Abstract [en]

    The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created. The first operation of the European X-ray free-electron laser facility accelerator based on superconducting technology is reported. The maximum electron energy is 17.5 GeV. A laser average power of 6 W is achieved at a photon energy of 9.3 keV.

  • 11.
    Bohm, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics.
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    ATLAS Level-1 Calorimeter Trigger: Subsystem Tests of a Jet/Energy-sum Processor Module2004In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 51, no 5, p. 2356-2361Article in journal (Refereed)
    Abstract [en]

    The ATLAS Level-1 Calorimeter Trigger consists of a Preprocessor, a Cluster Processor (CP), and a Jet/Energy-sum Processor (JEP). The CP and JEP receive digitized trigger-tower data from the Preprocessor and produce trigger multiplicities and total and missing energy for the final trigger decision. The trigger also provides region-of-interest information for the Level-2 trigger and intermediate results of the data acquisition system for monitoring and diagnostics by using Readout Driver modules. The JEP identifies and localizes jets, and sums total and missing transverse energy information from the trigger data. The Jet/Energy Module (JEM) is the main module of the JEP. The JEM prototype is designed to be functionally identical to the final production module for ATLAS and to have the full number of channels. Three JEM prototypes have been built and successfully tested. Various test vector patterns were used to test the energy summation and the jet algorithms. Data communication between adjacent JEMs and all other relevant modules of the JEP has been tested. Recent test results using the JEM prototypes are discussed.

  • 12.
    Bohm, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics.
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Pre-Production Validation of the ATLAS Level-1 Calorimeter Trigger System2006In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 53, no 3, p. 859-863Article in journal (Refereed)
    Abstract [en]

    The Level-1 Calorimeter Trigger is a major part of the first stage of event selection for the ATLAS experiment at the LHC. It is a digital, pipelined system with several stages of processing, largely based on FPGAs, which perform programmable algorithms in parallel with a fixed latency to process about 300 Gbyte/s of input data. The real-time output consists of counts of different types of trigger objects and energy sums. Prototypes of all module types have been undergoing intensive testing before final production during 2005. Verification of their correct operation has been performed stand-alone and in the ATLAS test-beam at CERN. Results from these investigations will be presented, along with a description of the methodology used to perform the tests.

  • 13.
    Bohm, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics.
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    The ATLAS Level-1 Calorimeter Trigger Architecture2004In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 51, no 3, p. 356-360Article in journal (Refereed)
    Abstract [en]

    The architecture of the ATLAS Level-1 Calorimeter Trigger system (L1Calo) is presented. Common approaches have been adopted for data distribution, result merging, readout, and slow control across the three different subsystems. A significant amount of common hardware is utilized, yielding substantial savings in cost, spares, and development effort. A custom, high-density backplane has been developed with data paths suitable for both the em/τ cluster processor (CP) and jet/energy-summation processor (JEP) subsystems. Common modules also provide interfaces to VME, CANbus and the LHC timing, trigger and control system (TTC). A common data merger module (CMM) uses field-programmable gate arrays (FPGAs) with multiple configurations for summing electron/photon and τ/hadron cluster multiplicities, jet multiplicities, or total and missing transverse energy. The CMM performs both crate- and system-level merging. A common, FPGA-based readout driver (ROD) is used by all of the subsystems to send input, intermediate and output data to the data acquisition (DAQ) system, and region-of-interest (RoI) data to the level-2 triggers. Extensive use of FPGAs throughout the system makes the trigger flexible and upgradable, and several architectural choices have been made to reduce the number of intercrate links and make the hardware more robust.

  • 14.
    Deoskar, Kunal
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jansson, Matti
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Observation of seasonal variations of the flux of high-energy atmospheric neutrinos with IceCube2023In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, no 9, article id 777Article in journal (Refereed)
    Abstract [en]

    Atmospheric muon neutrinos are produced by meson decays in cosmic-ray-induced air showers. The flux depends on meteorological quantities such as the air temperature, which affects the density of air. Competition between decay and re-interaction of those mesons in the first particle production generations gives rise to a higher neutrino flux when the air density in the stratosphere is lower, corresponding to a higher temperature. A measurement of a temperature dependence of the atmospheric ?mu, flux provides a novel method for constraining hadronic interaction models of air showers. It is particularly sensitive to the production of kaons. Studying this temperature dependence for the first time requires a large sample of high-energy neutrinos as well as a detailed understanding of atmospheric properties. We report the significant (> 10 s) observation of a correlation between the rate of more than 260,000 neutrinos, detected by IceCube between 2012 and 2018, and atmospheric tem-peratures of the stratosphere, measured by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's AQUA satellite. For the observed 10% seasonal change of effective atmospheric temperature we measure a 3.5(3)% change in the muon neutrino flux. This observed correlation deviates by about 2-3 standard deviations from the expected correla-tion of 4.3% as obtained from theoretical predictions under the assumption of various hadronic interaction models.

  • 15. Faatz, B.
    et al.
    Ploenjes, E.
    Ackermann, S.
    Agababyan, A.
    Asgekar, V.
    Ayvazyan, V.
    Baark, S.
    Baboi, N.
    Balandin, V.
    von Bargen, N.
    Bican, Y.
    Bilani, O.
    Boedewadt, J.
    Boehnert, M.
    Boespflug, R.
    Bonfigt, S.
    Bolz, H.
    Borges, F.
    Borkenhagen, O.
    Brachmanski, M.
    Braune, M.
    Brinkmann, A.
    Brovko, O.
    Bruns, T.
    Castro, P.
    Chen, J.
    Czwalinna, M. K.
    Damker, H.
    Decking, W.
    Degenhardt, M.
    Delfs, A.
    Delfs, T.
    Deng, H.
    Dressel, M.
    Duhme, H-T
    Duesterer, S.
    Eckoldt, H.
    Eislage, A.
    Felber, M.
    Feldhaus, J.
    Gessler, P.
    Gibau, M.
    Golubeva, N.
    Golz, T.
    Gonschior, J.
    Grebentsov, A.
    Grecki, M.
    Gruen, C.
    Grunewald, S.
    Hacker, K.
    Haenisch, L.
    Hage, A.
    Hans, T.
    Hass, E.
    Hauberg, A.
    Hensler, O.
    Hesse, M.
    Heuck, K.
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holz, M.
    Honkavaara, K.
    Hoeppner, H.
    Ignatenko, A.
    Jaeger, J.
    Jastrow, U.
    Kammering, R.
    Karstensen, S.
    Kaukher, A.
    Kay, H.
    Keil, B.
    Klose, K.
    Kocharyan, V.
    Koepke, M.
    Koerfer, M.
    Kook, W.
    Krause, B.
    Krebs, O.
    Kreis, S.
    Krivan, F.
    Kuhlmann, J.
    Kuhlmann, M.
    Kube, G.
    Laarmann, T.
    Lechner, C.
    Lederer, S.
    Leuschner, A.
    Liebertz, D.
    Liebing, J.
    Liedtke, A.
    Lilje, L.
    Limberg, T.
    Lipka, D.
    Liu, B.
    Lorbeer, B.
    Ludwig, K.
    Mahn, H.
    Marinkovic, G.
    Martens, C.
    Marutzky, F.
    Maslocv, M.
    Meissner, D.
    Mildner, N.
    Miltchev, V.
    Molnar, S.
    Mross, D.
    Mueller, F.
    Neumann, R.
    Neumann, P.
    Noelle, D.
    Obier, F.
    Pelzer, M.
    Peters, H-B
    Petersen, K.
    Petrosyan, A.
    Petrosyan, G.
    Petrosyan, L.
    Petrosyan, V.
    Petrov, A.
    Pfeiffer, S.
    Piotrowski, A.
    Pisarov, Z.
    Plath, T.
    Pototzki, P.
    Prandolini, M. J.
    Prenting, J.
    Priebe, G.
    Racky, B.
    Ramm, T.
    Rehlich, K.
    Riedel, R.
    Roggli, M.
    Roehling, M.
    Roensch-Schulenburg, J.
    Rossbach, J.
    Rybnikov, V.
    Schaefer, J.
    Schaffran, J.
    Schlarb, H.
    Schlesselmann, G.
    Schloesser, M.
    Schmid, P.
    Schmidt, C.
    Schmidt-Foehre, F.
    Schmitz, M.
    Schneidmiller, E.
    Schoeps, A.
    Scholz, M.
    Schreiber, S.
    Schuett, K.
    Schuetz, U.
    Schulte-Schrepping, H.
    Schulz, M.
    Shabunov, A.
    Smirnov, P.
    Sombrowski, E.
    Sorokin, A.
    Sparr, B.
    Spengler, J.
    Staack, M.
    Stadler, M.
    Stechmann, C.
    Steffen, B.
    Stojanovic, N.
    Sychev, V.
    Syresin, E.
    Tanikawa, T.
    Tavella, F.
    Tesch, N.
    Tiedtke, K.
    Tischer, M.
    Treusch, R.
    Tripathi, S.
    Vagin, P.
    Vetrov, P.
    Vilcins, S.
    Vogt, M.
    Wagner, A. de Zubiaurre
    Wamsat, T.
    Weddig, H.
    Weichert, G.
    Weigelt, H.
    Wentowski, N.
    Wiebers, C.
    Wilksen, T.
    Willner, A.
    Wittenburg, K.
    Wohlenberg, T.
    Wortmann, J.
    Wurth, W.
    Yurkov, M.
    Zagorodnov, I.
    Zemella, J.
    Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator2016In: New Journal of Physics, E-ISSN 1367-2630, Vol. 18, article id 062002Article in journal (Refereed)
    Abstract [en]

    Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.

  • 16.
    Hidvegi, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    A Small Portable Test System for the TileCal Digitizer System2008Conference paper (Refereed)
    Abstract [en]

    The hadronic Tile Calorimeter (TileCal) of the ATLAS detector at LHC has a digitization, pipeline and readout system composed of nearly 2000 boards [1][2], developed and maintained by Stockholm University. Prior to now a rather complex test system been used to verify the functionality of the boards. However this system was developed nearly 10 years ago and now difficult to maintain due to several already obsolete components. A new, simpler, more reliable, and portable test system was therefore initiated. Its components have been chosen to reduce problems with obsolescence, and to allow easy migration to new platforms over the lifetime of the digitizer system.

  • 17.
    Hidvegi, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Cederwall, Bo
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    A High-Speed Data Acquisition System for Segmented Ge-Detectors2006In: Nuclear Science Symposium Conference Record. IEEE, 2006, Vol. 1, p. 999-1001Conference paper (Refereed)
    Abstract [en]

    When using segmented Ge-detectors for gamma ray tracking it is necessary to determine the segment pulse shapes with high accuracy. A high-speed data acquisition system with many channels, high precision and with high sampling rate is required. To find the optimum performance, we are investigating what can be achieved by a system with extremely high sampling rates, 10 bits @2 GS/s. There are many other applications for such a system. Higher sampling rates usually mean lower bit resolution of the ADC, but with oversampling we expect to achieve a very good energy and time resolution. The system uses high performance FPGAs (Xilinx Virtex-IV) to cope with the data rates delivered by the high speed ADCs and to make all the data processing onboard in real time. Control and monitoring is implemented in an embedded soft processor. This processor is also in charge of the offboard gigabit Ethernet communication. The final system will consist of several separate boards, each with a number of input channels that will have to communicate with each other in real time over a high-speed communication link. The processed result will be transmitted over Ethernet to final storage. The project introduces many challenging issues, which are being addressed in turn with different prototype designs. These issues are: the ADC performance, interfacing the ADCs to the FPGA, implementing the flexible processing algorithms and high speed interconnection between the boards.

  • 18.
    Hidvegi, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Cederwall, Bo
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    A High-Speed Data Acquisition System for Segmented Ge-Detectors2007In: Nuclear Science Symposium Conference Record. IEEE, 2007, Vol. 1, p. 536-537Conference paper (Refereed)
    Abstract [en]

    When using segmented Ge-detectors for gamma ray tracking it is necessary to determine the segment pulse shapes with high accuracy. A high-speed data acquisition system with many channels, high precision and with high sampling rate is required. There are also many other applications for such a system. Our system uses high performance FPGAs (Xilinx Virtex-V [2]) to cope with the data rates delivered by the high speed ADC chosen (Atmel 2Gsps, 10 bits) and to make all the data processing onboard in real time. Each board contains four such ADCs, which can either handle four channels up to full speed, or achieve higher sampling rates with interleaving. The boards can communicate with each other over different types of high-speed communication links. Control and monitoring is implemented with embedded processors. The processed result will be transmitted over Ethernet to final storage. The project introduces many challenging issues: signal integrity, ADC performance, interfacing ADCs to the FPGA, synchronisation of ADCs across the entire system, implementing flexible processing algorithms, high speed interconnection between boards and managing the significant heat generation. This is an ongoing project with interesting potentials for the future.

  • 19.
    Hidvegi, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Gessler, Patrick
    Deutsches Elektronen-Synchrotron (DESY).
    Rehlich, Kay
    Deutsches Elektronen-Synchrotron (DESY),.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    An Advanced FPGA Based Phase-Lock-Loop System as an Alternative Solution for the XFEL Timing System2009In: Nuclear Science Symposium Conference Record (NSS/MIC), 2009 IEEE, 2009, p. 1871-1872Conference paper (Refereed)
    Abstract [en]

    The European XFEL project requires a high-speed, very precise clock and timing distribution over large distances. A prototype system which fulfils current requirements that uses high-end components has just been completed and is being tested. However, the system is quite complicated and the boards are very complex, being designed using the small micro-TCA form factor. A way to simplify the system, and perhaps reduce cost, would be to implement an Advanced PLL in the programmable logic of an FPGA, which then would control an external VCO. By doing so several major issues could be resolved at the same time, while making more use of the advanced features of modern FPGAs. Such a system could be an alternative solution to the complex part of the Timing and Triggering System for XFEL.

  • 20.
    Hidvegi, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Gessler, Patrick
    Deutsches Elektronen-Synchrotron (DESY).
    Rehlich, Kay
    Deutsches Elektronen-Synchrotron (DESY),.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Timing and Triggering System Prototype for the XFEL Project2010In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 58, no 4, p. 1852-1856Article in journal (Refereed)
    Abstract [en]

    The European X-ray Free Electron Laser (XFEL) [1] at DESY in Hamburg will begin operating in the next few years, enabling new, ground-breaking research opportunities. The entire system requires very precise clock and trigger distribution, synchronous with the 1.3 GHz system RF-frequency, over distances of more than 3.4 km. The new experiment demanded features that other commercial solutions could not yet provide. Researchers at Stockholm University and DESY have developed a prototype for the timing system of XFEL. It has been decided that XFEL will use modern ATCA and Micro-TCA systems because of their advanced features and reliability. The timing system has been adapted to the Micro-TCA bus standard and also follows the new upcoming xTCA for physics standard. The prototype is fully functional and complete. It will serve as a platform for future development of the whole timing system. This paper describes the hardware design and some test results using the prototype board.

  • 21.
    Hidvegi, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Gessler, Patrick
    Deutsches Elektronen-Synchrotron (DESY).
    Rehlich, Kay
    Deutsches Elektronen-Synchrotron (DESY),.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Rydström, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    A System for Distributing High-Speed Synchronous High-Precision Clock and Trigger Data over Large Distances2008In: Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE, 2008, p. 2581-2584Conference paper (Refereed)
    Abstract [en]

    The distribution of precise timing throughout the European X-ray Free Electron Laser project [1] (XFEL) and its triggering system is a very challenging part of the system design. ADCs in data acquisition systems and DACs in control systems will require very high precision clocks. The clocks need to be synchronous to each other, both in frequency and phase, with a jitter performance better than 5 ps (RMS). At some high-speed ADCs it might even need a precision down to 0.1ps. The frequencies that must be available are the main 1.3 GHz and some frequencies below, which are all derived from the main frequency. The phase needs to be adjustable to allow synchronization between separate devices.

  • 22.
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    FPGA-based Instrumentation for Advanced Physics Experiments2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Modern physical experiments often demand advanced instrumentation based on advances in  technology. This work describes four instrumentation physics projects that are based on modern, high-capacity Field-Programmable Gate Arrays, making use of their versatility, programmability, high bandwidth communication interfaces and signal processing capabilities.

    In the first project, a jet-finding algorithm for the ATLAS detector at the LHC experiment at CERN was developed and implemented, and different verification methods were created to validate the functionality and reliability. The experiment uses a three level trigger system, where the first level uses custom FPGA-based hardware for analysis of collision events in real-time.

    The second project was an advanced timing and triggering distribution system for the new European X-Ray Free Electron Laser (XFEL) facility at DESY in Hamburg. XFEL will enable scientists to study nano structures on the atomic scale. Its laser pulses will have the strongest peak power in the world with extremely short duration and a high repetition rate, which will even allow filming of chemical reactions. The timing system uses modern FPGAs to distribute high-speed signals over optical fibers and to deliver clocks and triggers with high accuracy.

    The third project was a new data acquisition board based on high-speed ADCs combined with high-performance FPGAs, to process data from segmented Ge-detectors in real-time. The aim was to improve system performance by greatly oversampling and filtering the analog signals to achieve greater effective resolution.

    Finally, an innovative solution was developed to replace an aging system used at CERN and Stockholm University to test vital electronics in the Tile Calorimeters of the ATLAS detector system. The new system is entirely based on a commercial FPGA development board, where all necessary custom communication protocols were implemented in firmware to emulate obsolete hardware.

    Download full text (pdf)
    fulltext
  • 23.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Bergeås, Elin
    Stockholm University, Faculty of Science, Department of Physics.
    Berglund, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics.
    Engström, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics.
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics.
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics.
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    The ATLAS Experiment at the CERN Large Hadron Collider2008In: Journal of Instrumentation, no 3, p. S08003-Article in journal (Refereed)
  • 24.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Bergeås Kuutmann, Elin
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Hillert, Sonja
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics.
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics.
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics.
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Charged-Particle Multiplicities in pp Interactions at $\sqrt{s}=900$ GeV Measured with the ATLAS Detector at the LHC2010In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 688, no 1, p. 21-42Article in journal (Refereed)
    Abstract [en]

    The first measurements from proton–proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range |η|<2.5 and pT>500 MeV. The measurements are compared to Monte Carlo models of proton–proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity at η=0 is measured to be 1.333±0.003(stat.)±0.040(syst.), which is 5–15% higher than the Monte Carlo models predict

  • 25.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Bergeås Kuutmann, Elin
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Hillert, Sonja
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics.
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics.
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics.
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Study of Energy Response and Resolution of the ATLAS Barrel Calorimeter to Hadrons of Energies from 20 to 350 GeV2010In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 621, no 1-3, p. 134-150Article in journal (Refereed)
    Abstract [en]

    We report on the results of the search for extremely-high energy neutrinos with energies above 107 GeV obtained with the partially (∼30%) constructed IceCube in 2007. From the absence of signal events in the sample of 242.1 days of effective live time, we derive a 90% C.L. model independent differential upper limit based on the number of signal events per energy decade at E2ϕνeμτ≃1.4×10-6 GeV cm-2 sec⁡-1 sr-1 for neutrinos in the energy range from 3×107 to 3×109 GeV

  • 26.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Bergeås Kuutmann, Elin
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Hillert, Sonja
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics.
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics.
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic Calorimeter using Cosmic Muons2010In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 70, no 3, p. 755-785Article in journal (Refereed)
    Abstract [en]

    The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps. This leads to an estimated contribution to the constant term of % in the barrel and % in the endcaps. The same data are used to measure the drift velocity of ionization electrons in liquid argon, which is found to be 4.61±0.07 mm/μs at 88.5 K and 1 kV/mm.

  • 27.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Bergeås Kuutmann, Elin
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics.
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics.
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Readiness of the ATLAS Liquid Argon Calorimeter for LHC Collisions2010In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 70, no 3, p. 723-753Article in journal (Refereed)
    Abstract [en]

    The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along η (averaged over φ) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained using the ATLAS readout, data acquisition, and reconstruction software indicate that the liquid argon calorimeter is well-prepared for collisions at the dawn of the LHC era

  • 28.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clement, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Search for New Phenomena in $t\bar{t}$ Events With Large Missing Transverse Momentum in Proton-Proton Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2012In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 108, article id 041805Article in journal (Refereed)
    Abstract [en]

    A search for new phenomena in tt̅ events with large missing transverse momentum in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The measurement is based on 1.04  fb-1 of data collected with the ATLAS detector at the LHC. Contributions to this final state may arise from a number of standard model extensions. The results are interpreted in terms of a model where new top-quark partners are pair produced and each decay to an on-shell top (or antitop) quark and a long-lived undetected neutral particle. The data are found to be consistent with standard model expectations. A limit at 95% confidence level is set excluding a cross section times branching ratio of 1.1 pb for a top-partner mass of 420 GeV and a neutral particle mass less than 10 GeV. In a model of exotic fourth generation quarks, top-partner masses are excluded up to 420 GeV and neutral particle masses up to 140 GeV.

  • 29.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, M.
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of $W\gamma$ and $Z\gamma$ Production in Proton-Proton Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 09, p. 072-Article in journal (Refereed)
    Abstract [en]

    We present studies of W and Z bosons with associated high energy photons produced in pp collisions at root s = 7 TeV. The analysis uses 35 pb(-1) of data collected by the ATLAS experiment in 2010. The event selection requires W and Z bosons decaying into high pT leptons (electrons or muons) and a photon with E(T) > 15 GeV separated from the lepton(s) by a distance Delta R(l, gamma) > 0.7 in eta-phi space. A total of 95 (97) pp -> e(+/-)nu gamma + X (pp -> mu(+/-)nu gamma + X) and 25 (23) pp -> e(+)e(-)gamma + X (pp -> mu(+)mu(-)gamma + X) event candidates are selected. The kinematic distributions of the leptons and photons and the production cross sections are measured. The data are found to agree with Standard Model predictions that include next-to-leading-order O(alpha alpha(s)) contributions.

  • 30.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvegi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Karl-Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, J.
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, M.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sellden, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV2013In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 73, no 3, p. 2304-Article in journal (Refereed)
    Abstract [en]

    The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of root s = 7 TeV corresponding to an integrated luminosity of 38 pb(-1). Jets are reconstructed with the anti-k(t) algorithm with distance parameters R = 0.4 or R = 0.6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT >= 20 GeV and pseudorapidities vertical bar eta vertical bar < 4.5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2.5 % in the central calorimeter region (vertical bar eta vertical bar < 0.8) for jets with 60 <= p(T) < 800 GeV, and is maximally 14 % for p(T) < 30 GeV in the most forward region 3.2 <= vertical bar eta vertical bar < 4.5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon p(T), the sum of the transverse momenta of tracks associated to the jet, or a system of low-p(T) jets recoiling against a high-p(T) jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-p(T) jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined.

  • 31.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics.
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Hillert, Sonja
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics.
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics.
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics.
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Performance of the ATLAS Detector using First Collision Data2010In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 9, p. 056-Article in journal (Refereed)
  • 32.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    A Measurement of the Ratio of the W and Z Cross Sections with Exactly one Associated jet in pp Collisions at $\sqrt{s}=7$ TeV with ATLAS2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 708, p. 221-240Article in journal (Refereed)
    Abstract [en]

    The ratio of production cross sections of the W and Z bosons with exactly one associated jet is presented as a function of jet transverse momentum threshold. The measurement has been designed to maximise cancellation of experimental and theoretical uncertainties, and is reported both within a particle-level kinematic range corresponding to the detector acceptance and as a total cross-section ratio. Results are obtained with the ATLAS detector at the LHC in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity of 33 pb−1. The results are compared with perturbative leading-order, leading-log, and next-to-leading-order QCD predictions, and are found to agree within experimental and theoretical uncertainties. The ratio is measured for events with a single jet with pT>30 GeV to be 8.73±0.30(stat)±0.40(syst) in the electron channel, and 8.49±0.23(stat)±0.33(syst) in the muon channel.

  • 33.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Inclusive Search for Same-Sign Dilepton Signatures in pp Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 10, p. 107-Article in journal (Refereed)
    Abstract [en]

    An inclusive search is presented for new physics in events with two isolated leptons (e or μ) having the same electric charge. The data are selected from events collected from pp collisions at Ös = 7 \sqrt {s} = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb−1. The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, and μμ channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks.

  • 34.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Limits on the Production of the Standard Model Higgs Boson in pp Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 71, no 9, p. 1728-Article in journal (Refereed)
    Abstract [en]

    A search for the Standard Model Higgs boson at the Large Hadron Collider (LHC) running at a centre-of-mass energy of 7 TeV is reported, based on a total integrated luminosity of up to 40 pb(-1) collected by the ATLAS detector in 2010. Several Higgs boson decay channels: H -> gamma gamma, H -> ZZ(()*()) -> llll, H -> ZZ -> LL nu nu, H -> ZZ -> llqq, H -> WW(()*()) -> l nu l nu and H -> WW -> l nu qq (l is e, mu) are combined in a mass range from 110 GeV to 600 GeV. The highest sensitivity is achieved in the mass range between 160 GeV and 170 GeV, where the expected 95% CL exclusion sensitivity is at Higgs boson production cross sections 2.3 times the Standard Model prediction. Upper limits on the cross section for its production are determined. Models with a fourth generation of heavy leptons and quarks with Standard Model-like couplings to the Higgs boson are also investigated and are excluded at 95% CL for a Higgs boson mass in the range from 140 GeV to 185 GeV.

  • 35.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of Multi-Jet Cross Sections in Proton-Proton Collisions at a 7 TeV Center-of-Mass Energy2011In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 71, no 11, p. 1763-Article in journal (Refereed)
    Abstract [en]

    Inclusive multi-jet production is studied in proton–proton collisions at a center-of-mass energy of 7 TeV, using the ATLAS detector. The data sample corresponds to an integrated luminosity of 2.4 pb−1. Results on multi-jet cross sections are presented and compared to both leading-order plus parton-shower Monte Carlo predictions and to next-to-leading-order QCD calculations.

  • 36.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Differential Cross-Sections of Inclusive, Prompt and Non-Prompt $J/\psi$ Production in Proton-Proton Collisions at $\sqrt{s}=7$ TeV2011In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 850, no 3, p. 387-444Article in journal (Refereed)
  • 37.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Inclusive and Dijet Cross-Sections of b-jets in pp Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 71, no 12, p. 1846-Article in journal (Refereed)
    Abstract [en]

    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of root s = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb(-1). The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < p(T) < 400 GeV and rapidity in the range vertical bar y vertical bar < 2.1. The b<(b)over bar>-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m(jj) < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured b (b) over bar -dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.

  • 38.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the inclusive isolated prompt photon cross-section in pp collisions at root s=7 TeV using 35 pb(-1) of ATLAS data2011In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 706, no 2-3, p. 150-167Article in journal (Refereed)
    Abstract [en]

    A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy root s = 7 TeV is presented. The measurement covers the pseudorapidity ranges vertical bar eta vertical bar < 1.37 and 1.52 <= vertical bar eta vertical bar < 2.37 in the transverse energy range 45 <= E(T) < 400 GeV. The results are based on an integrated luminosity of 35 pb(-1), collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.

  • 39.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Inelastic Proton-Proton Cross-Section at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: Nature Communications, E-ISSN 2041-1723, Vol. 2, p. 463-Article in journal (Refereed)
    Abstract [en]

    The dependence of the rate of proton-proton interactions on the centre-of-mass collision energy, root s, is of fundamental importance for both hadron collider physics and particle astrophysics. The dependence cannot yet be calculated from first principles; therefore, experimental measurements are needed. Here we present the first measurement of the inelastic proton-proton interaction cross-section at a centre-of-mass energy, root s, of 7 TeV using the ATLAS detector at the Large Hadron Collider. Events are selected by requiring hits on scintillation counters mounted in the forward region of the detector. An inelastic crosssection of 60.3 +/- 2.1 mb is measured for xi > 5x10(-6), where xi is calculated from the invariant mass, M(X), of hadrons selected using the largest rapidity gap in the event. For diffractive events, this corresponds to requiring at least one of the dissociation masses to be larger than 15.7 GeV.

  • 40.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Isolated Diphoton Cross Section in pp Collisions at √s=7 TeV with the ATLAS Detector2012In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 85, p. 012003-Article in journal (Refereed)
    Abstract [en]

    The ATLAS experiment has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at √s=7  TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37  pb-1. The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross sections, as functions of the di-photon mass (mγγ), total transverse momentum (pT,γγ), and azimuthal separation (Δϕγγ), are presented and compared to the predictions of next-to-leading-order QCD.

  • 41.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Jet Fragmentation Function and Transverse Profile in Proton-Proton Collisions at a Center-of-Mass Energy of 7 TeV with the ATLAS Detector2011In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 71, no 11, p. 1795-Article in journal (Refereed)
    Abstract [en]

    The jet fragmentation function and transverse profile for jets with 25 GeV < p(Tjet) < 500 GeV and |eta(jet)| < 1.2 produced in proton-proton collisions with a center-of-mass energy of 7 TeV are presented. The measurement is performed using data with an integrated luminosity of 36 pb(-1). Jets are reconstructed and their momentum measured using calorimetric information. The momenta of the charged particle constituents are measured using the tracking system. The distributions corrected for detector effects are compared with various Monte Carlo event generators and generator tunes. Several of these choices show good agreement with the measured fragmentation function. None of these choices reproduce both the transverse profile and fragmentation function over the full kinematic range of the measurement.

  • 42.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the pseudorapidity and transverse momentum dependence of the elliptic flow of charged particles in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 707, no 3-4, p. 330-348Article in journal (Refereed)
    Abstract [en]

    This Letter describes the measurement of elliptic flow of charged particles in lead-lead collisions at root s(NN) = 2.76 TeV using the ATLAS detector at the Large Hadron Collider (LHC). The results are based on an integrated luminosity of approximately 7 mu b(-1). Elliptic flow is measured over a wide region in pseudorapidity, vertical bar eta vertical bar < 2.5, and over a broad range in transverse momentum, 0.5 < p(T) < 20 GeV. The elliptic flow parameter nu(2) is obtained by correlating individual tracks with the event plane measured using energy deposited in the forward calorimeters. As a function of transverse momentum, nu(2)(p(T)) reaches a maximum at p(T) of about 3 GeV. then decreases and becomes weakly dependent on p(T) above 7-8 GeV. Over the measured pseudorapidity region, nu(2) is found to be only weakly dependent on eta, with less variation than observed at lower beam energies. The results are discussed in the context of previous measurements at lower collision energies, as well as recent results from the LHC.

  • 43.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Top Quark Pair Production Cross Section in pp Collisions at $\sqrt{s}=7$ TeV in Dilepton Final States with ATLAS2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 707, p. 459-477Article in journal (Refereed)
    Abstract [en]

    A measurement of the production cross section of top quark pairs () in proton–proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the Large Hadron Collider is reported. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. Using a data sample corresponding to an integrated luminosity of 35 pb−1, a production cross section is measured for an assumed top quark mass of mt=172.5 GeV. A second measurement requiring at least one jet identified as coming from a b quark yields a comparable result, demonstrating that the dilepton final states are consistent with being accompanied by b-quark jets. These measurements are in good agreement with Standard Model predictions.

  • 44.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics.
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the transverse momentum distribution of W bosons in pp collisions at √s=7  TeV with the ATLAS detector2012In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 85, no 1, p. 012005-1-012005-30Article in journal (Refereed)
    Abstract [en]

    This paper describes a measurement of the W boson transverse momentum distribution using ATLAS pp collision data from the 2010 run of the LHC at √s=7  TeV, corresponding to an integrated luminosity of about 31  pb-1. Events form both W→eν and W→μν are used, and the transverse momentum of the W candidates is measured through the energy deposition in the calorimeter from the recoil of the W. The resulting distributions are unfolded to obtain the normalized differential cross sections as a function of the W boson transverse momentum. We present results for pTW<300  GeV in the electron and muon channels as well as for their combination, and compare the combined results to the predictions of perturbative QCD and a selection of event generators.

  • 45.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Transverse Momentum Distribution of $Z/\gamma^\ast$ Bosons in Proton-Proton Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 705, no 5, p. 415-434Article in journal (Refereed)
    Abstract [en]

    A measurement of the Z/gamma* transverse momentum (p(T)(Z)) distribution in proton-proton collisions at root s = 7 TeV is presented using Z/gamma* -> e(+)e(-) and Z/gamma* -> mu(+)mu(-) decays collected with the ATLAS detector in data sets with integrated luminosities of 35 pb(-1) and 40 pb(-1), respectively. The normalized differential cross sections are measured separately for electron and muon decay channels as well as for their combination up to pi of 350 GeV for invariant dilepton masses 66 GeV < m(ll) < 116 GeV. The measurement is compared to predictions of perturbative QCD and various event generators. The prediction of resummed QCD combined with fixed order perturbative QCD is found to be in good agreement with the data.

  • 46.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the $\Upsilon(1S)$ Production Cross-Section in pp Collisions at $\sqrt{s}=7$ TeV in ATLAS2011In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 705, no 1-2, p. 9-27Article in journal (Refereed)
  • 47.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the W Charge Asymmetry in the $W\to\mu\nu$ Decay Mode in pp Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2011In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 701, no 1, p. 31-49Article in journal (Refereed)
    Abstract [en]

    This Letter reports a measurement of the muon charge asymmetry from W bosons produced in proton–proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS experiment at the LHC. The asymmetry is measured in the Wμν decay mode as a function of the muon pseudorapidity using a data sample corresponding to a total integrated luminosity of 31 pb−1. The results are compared to predictions based on next-to-leading order calculations with various parton distribution functions. This measurement provides information on the u and d quark momentum fractions in the proton.

  • 48.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the Wτντ Cross Section in pp Collisions at √s=7 TeV with the ATLAS Experiment2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 706, p. 276-294Article in journal (Refereed)
  • 49.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurement of the $Z\to\tau\tau$ Cross Section with the ATLAS Detector2011In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 84, no 11, p. 112006-Article in journal (Refereed)
    Abstract [en]

     The Z -> tau tau cross section is measured with the ATLAS experiment at the LHC in four different final states determined by the decay modes of the tau leptons: muon-hadron, electron-hadron, electron-muon, and muon-muon. The analysis is based on a data sample corresponding to an integrated luminosity of 36 pb(-1), at a proton-proton center-of-mass energy of root s = 7 TeV. Cross sections are measured separately for each final state in fiducial regions of high detector acceptance, as well as in the full phase space, over the mass region 66-116 GeV. The individual cross sections are combined and the product of the total Z production cross section and Z -> tau tau branching fraction is measured to be 0.97 +/- 0.07(stat) +/- 0.06(syst) +/- 0: 03(lumi) nb, in agreement with next-to-next-to-leading order calculations.

  • 50.
    Åsman, Barbro
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Clément, Christophe
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Eriksson, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Gellerstedt, Karl
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hellman, Sten
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hidvégi, Attila
    Stockholm University, Faculty of Science, Department of Physics.
    Holmgren, Sven-Olof
    Stockholm University, Faculty of Science, Department of Physics.
    Johansen, Marianne
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johansson, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Jon-And, Kerstin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lesser, Jonas
    Stockholm University, Faculty of Science, Department of Physics.
    Lundberg, Johan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Milstead, David
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Moa, Torbjörn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Nordkvist, Björn
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Papadelis, Aras
    Stockholm University, Faculty of Science, Department of Physics.
    Ramstedt, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Selldén, Björn
    Stockholm University, Faculty of Science, Department of Physics.
    Silverstein, Samuel
    Stockholm University, Faculty of Science, Department of Physics.
    Sjölin, Jörgen
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strandberg, Sara
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tylmad, Maja
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Measurements of the Electron and Muon Inclusive Cross-Sections in Proton-Proton Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 707, p. 438-458Article in journal (Refereed)
    Abstract [en]

    This Letter presents measurements of the differential cross-sections for inclusive electron and muon production in proton–proton collisions at a centre-of-mass energy of , using data collected by the ATLAS detector at the LHC. The muon cross-section is measured as a function of pT in the range 4<pT<100 GeV and within pseudorapidity |η|<2.5. In addition the electron and muon cross-sections are measured in the range 7<pT<26 GeV and within |η|<2.0, excluding 1.37<|η|<1.52. Integrated luminosities of 1.3 pb−1 and 1.4 pb−1 are used for the electron and muon measurements, respectively. After subtraction of the W/Z/γ contribution, the differential cross-sections are found to be in good agreement with theoretical predictions for heavy-flavour production obtained from Fixed Order NLO calculations with NLL high-pT resummation, and to be sensitive to the effects of NLL resummation.

123 1 - 50 of 109
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf