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Lundberg, Johan
Publications (10 of 264) Show all publications
Athron, P., Balazs, C., Bringmann, T., Buckley, A., Chrzaszcz, M., Conrad, J., . . . Wild, S. (2018). GAMBIT: the global and modular beyond-the-standard-model inference tool. European Physical Journal C, 78(2), Article ID 98.
Open this publication in new window or tab >>GAMBIT: the global and modular beyond-the-standard-model inference tool
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2018 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, no 2, article id 98Article in journal (Refereed) Published
Abstract [en]

In Ref. (GAMBIT Collaboration: Athron et. al., Eur. Phys. J. C. arXiv: 1705.07908, 2017) we introduced the global-fitting framework GAMBIT. In this addendum, we describe a new minor version increment of this package. GAMBIT 1.1 includes full support for Mathematica backends, which we describe in some detail here. As an example, we backend SUSYHD (Vega and Villadoro, JHEP 07: 159, 2015), which calculates the mass of the Higgs boson in the MSSM from effective field theory. We also describe updated likelihoods in PrecisionBit and DarkBit, and updated decay data included in DecayBit.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-153736 (URN)10.1140/epjc/s10052-017-5513-2 (DOI)000424102700001 ()
Available from: 2018-03-06 Created: 2018-03-06 Last updated: 2022-03-23Bibliographically approved
Åsman, B., Bendtz, K., Bohm, C., Hellman, S., Johansen, M., Lundberg, J., . . . Sjölin, J. (2016). The ATLAS Data Acquisition and High Level Trigger system. Journal of Instrumentation, 11, Article ID P06008.
Open this publication in new window or tab >>The ATLAS Data Acquisition and High Level Trigger system
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2016 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 11, article id P06008Article in journal (Refereed) Published
Abstract [en]

This paper describes the data acquisition and high level trigger system of the ATLAS experiment at the Large Hadron Collider at CERN, as deployed during Run 1. Data flow as well as control, configuration and monitoring aspects are addressed. An overview of the functionality of the system and of its performance is presented and design choices are discussed.

Keywords
Control and monitor systems online, Data acquisition concepts, Online farms and, online filtering, Trigger concepts and systems (hardware and software)
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-132414 (URN)10.1088/1748-0221/11/06/P06008 (DOI)000379239700020 ()
Available from: 2016-08-12 Created: 2016-08-11 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia, O., Bohm, C., Clément, C., . . . Tylmad, M. (2015). Jet energy measurement and its systematic uncertainty in proton-proton collisions at root s=7 TeV with the ATLAS detector. European Physical Journal C, 75(1), Article ID 17.
Open this publication in new window or tab >>Jet energy measurement and its systematic uncertainty in proton-proton collisions at root s=7 TeV with the ATLAS detector
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2015 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 75, no 1, article id 17Article in journal (Refereed) Published
Abstract [en]

The jet energy scale (JES) and its systematic uncertainty are determined for jetsmeasured with the ATLAS detector using proton-proton collision data with a centre-of-mass energy of root s = 7 TeV corresponding to an integrated luminosity of 4.7 fb(-1). Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti-kt algorithmwith distance parameters R = 0.4 or R = 0.6, and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a Z boson, for 20 <= p(T)(jet) < 1000 GeV and pseudorapidities vertical bar eta vertical bar < 4.5. The effect of multiple proton-proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1% is found in the central calorimeter region (vertical bar eta vertical bar| < 1.2) for jets with 55 = p(T)(jet) < 500 GeV. For central jets at lower p(T), the uncertainty is about 3%. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton-proton collisions and test-beam data, which also provide the estimate for p(T)(jet) > 1 TeV. The calibration of forward jets is derived from dijet p(T) balance measurements. The resulting uncertainty reaches its largest value of 6% for low-p(T) jets at vertical bar eta vertical bar| = 4.5. Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5-3%.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-115458 (URN)10.1140/epjc/s10052-014-3190-y (DOI)000348991900001 ()
Note

AuthorCount:2934;

Available from: 2015-03-26 Created: 2015-03-24 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia, O., Bohm, C., Clément, C., . . . Tylmad, M. (2014). Measurement of chi(c1) and chi(c2) production with root s=7 TeV pp collisions at ATLAS. Journal of High Energy Physics (JHEP) (7), 154
Open this publication in new window or tab >>Measurement of chi(c1) and chi(c2) production with root s=7 TeV pp collisions at ATLAS
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2014 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 7, p. 154-Article in journal (Refereed) Published
Abstract [en]

The prompt and non-prompt production cross-sections for the chi(c1) and chi(c2) charmonium states are measured in pp collisions at root s = 7TeV with the ATLAS detector at the LHC using 4.5 fb(-1) of integrated luminosity. The chi(c) states are reconstructed through the radiative decay chi c -> J/psi gamma ( with J/psi -> mu(+)mu(-)) where photons are reconstructed from gamma -> e(+)e(-) conversions. The production rate of the chi(c2) state relative to the chi(c1) state is measured for prompt and non-prompt chi(c) as a function of J/psi transverse momentum. The prompt chi(c) cross-sections are combined with existing measurements of prompt J/psi production to derive the fraction of prompt J/psi produced in feed-down from chi(c) decays. The fractions of chi(c1) and chi(c2) produced in b-hadron decays are also measured.

Keywords
Hadron-Hadron Scattering
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-107630 (URN)10.1007/JHEP07(2014)154 (DOI)000340391300001 ()
Note

AuthorCount:2960;

Available from: 2014-09-22 Created: 2014-09-22 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia, O., Bohm, C., Clément, C., . . . Tylmad, M. (2014). Measurement of dijet cross-sections in pp collisions at 7 TeV centre-of-mass energy using the ATLAS detector. Journal of High Energy Physics (JHEP) (5), 059
Open this publication in new window or tab >>Measurement of dijet cross-sections in pp collisions at 7 TeV centre-of-mass energy using the ATLAS detector
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2014 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, p. 059-Article in journal (Refereed) Published
Abstract [en]

Double-differential dijet cross-sections measured in pp collisions at the LHC with a 7 TeV centre-of-mass energy are presented as functions of dijet mass and half the rapidity separation of the two highest-p(T) jets. These measurements are obtained using data corresponding to an integrated luminosity of 4.5 fb(-1), recorded by the ATLAS detector in 2011. The data are corrected for detector effects so that cross-sections are presented at the particle level. Cross-sections are measured up to 5 TeV dijet mass using jets reconstructed with the anti-k(t) algorithm for values of the jet radius parameter of 0.4 and 0.6. The cross-sections are compared with next-to-leading-order perturbative QCD calculations by NLOJet++ corrected to account for non-perturbative effects. Comparisons with POWHEG predictions, using a next-to-leading-order matrix element calculation interfaced to a parton-shower Monte Carlo simulation, are also shown. Electroweak effects are accounted for in both cases. The quantitative comparison of data and theoretical predictions obtained using various parameterizations of the parton distribution functions is performed using a frequentist method. In general, good agreement with data is observed for the NLOJet++ theoretical predictions when using the CT10, NNPDF2.1 and MSTW 2008 PDF sets. Disagreement is observed when using the ABM11 and HERAPDF1.5 PDF sets for some ranges of dijet mass and half the rapidity separation. An example setting a lower limit on the compositeness scale for a model of contact interactions is presented, showing that the unfolded results can be used to constrain contributions to dijet production beyond that predicted by the Standard Model.

Keywords
Jets, Jet physics, Hadron-Hadron Scattering
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-106106 (URN)10.1007/JHEP05(2014)059 (DOI)000336740400001 ()
Note

AuthorCount:2951;

Available from: 2014-07-23 Created: 2014-07-21 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bohm, C., Clément, C., Eriksson, D., . . . Yang, Z. (2014). Measurement of the inclusive isolated prompt photons cross section in pp collisions at root s=7 TeV with the ATLAS detector using 4.6 fb(-1). Physical Review D, 89(5), 052004
Open this publication in new window or tab >>Measurement of the inclusive isolated prompt photons cross section in pp collisions at root s=7 TeV with the ATLAS detector using 4.6 fb(-1)
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2014 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 89, no 5, p. 052004-Article in journal (Refereed) Published
Abstract [en]

A measurement of the cross section for the production of isolated prompt photons in pp collisions at a center-of-mass energy root s = 7 TeV is presented. The results are based on an integrated luminosity of 4.6 fb(-1) collected with the ATLAS detector at the LHC. The cross section is measured as a function of photon pseudorapidity eta(gamma) and transverse energy E-T(gamma) in the kinematic range 100 <= E-T(gamma) < 1000 GeV and in the regions vertical bar eta(gamma)vertical bar < 1.37 and 1.52 <= vertical bar eta(gamma)vertical bar < 2.37. The results are compared to leading-order parton-shower Monte Carlo models and next-to-leading-order perturbative QCD calculations. Next-to-leading-order perturbative QCD calculations agree well with the measured cross sections as a function of E-T(gamma) and eta(gamma) .

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-103986 (URN)10.1103/PhysRevD.89.052004 (DOI)000334304700002 ()
Note

AuthorCount:2916;

Available from: 2014-06-02 Created: 2014-05-27 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia, O., Bohm, C., Clément, C., . . . Tylmad, M. (2014). Measurement of the mass difference between top and anti-top quarks in pp collisions at root s=7 TeV using the ATLAS detector. Physics Letters B, 728, 363-379
Open this publication in new window or tab >>Measurement of the mass difference between top and anti-top quarks in pp collisions at root s=7 TeV using the ATLAS detector
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2014 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 728, p. 363-379Article in journal (Refereed) Published
Abstract [en]

A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb(-1) data sample of proton-proton collisions at root s = 7 TeV recorded with the ATLAS detector at the LHC, events consistent with t (t) over bar production and decay into a single charged lepton final state are reconstructed. For each event, the mass difference between the top and anti-top quark candidate is calculated. A two b-tag requirement is used in order to reduce the background contribution. A maximum likelihood fit to these per-event mass differences yields Delta m = m(t) - m((t) over bar) = 0.67 +/- 0.61 (stat) +/- 0.41 (syst) GeV, consistent with CPT invariance.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-102087 (URN)10.1016/j.physletb.2013.12.010 (DOI)000330556000059 ()
Note

AuthorCount:2936;

Available from: 2014-03-27 Created: 2014-03-26 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia, O., Bohm, C., Clément, C., . . . Yang, Z. (2014). Measurement of the production cross section of prompt j/psi mesons in association with a W (+/-) boson in pp collisions root s=7 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (4), Article ID 172.
Open this publication in new window or tab >>Measurement of the production cross section of prompt j/psi mesons in association with a W (+/-) boson in pp collisions root s=7 TeV with the ATLAS detector
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2014 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 4, article id 172Article in journal (Refereed) Published
Abstract [en]

The process pp -> W (+/-) J/psi provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb(-1) of root s= 7 TeV pp collisions at the LHC, the first observation is made of the production of W (+/-) + prompt J/psi events in hadronic collisions, using W (+/-) -> mu nu(mu) and J/psi -> mu(+)mu(-) center dot A yield of W (+/-) + prompt J/psi events is observed, with a statistical significance of 5.1 sigma. The production rate as a ratio to the inclusive W (+/-) boson production rate is measured, and the double parton scattering contribution to the cross section is estimated.

Keywords
Hadron-Hadron Scattering
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-144364 (URN)10.1007/JHEP04(2014)172 (DOI)000335732000001 ()
Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia, O., Bohm, C., Clément, C., . . . Yang, Z. (2014). Measurement of the top quark pair production charge asymmetry in proton-proton collisions at root s=7 TeV using the ATLAS detector. Journal of High Energy Physics (JHEP) (2), 107
Open this publication in new window or tab >>Measurement of the top quark pair production charge asymmetry in proton-proton collisions at root s=7 TeV using the ATLAS detector
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2014 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, p. 107-Article in journal (Refereed) Published
Abstract [en]

This paper presents a measurement of the top quark pair () production charge asymmetry A (C) using 4.7 fb(-1) of proton-proton collisions at a centre-of-mass energy root s = 7 TeV collected by the ATLAS detector at the LHC. A -enriched sample of events with a single lepton (electron or muon), missing transverse momentum and at least four high transverse momentum jets, of which at least one is tagged as coming from a b-quark, is selected. A likelihood fit is used to reconstruct the event kinematics. A Bayesian unfolding procedure is employed to estimate A (C) at the parton-level. The measured value of the production charge asymmetry is A (C) = 0.006 +/- 0.010, where the uncertainty includes both the statistical and the systematic components. Differential A (C) measurements as a function of the invariant mass, the rapidity and the transverse momentum of the system are also presented. In addition, A (C) is measured for a subset of events with large velocity, where physics beyond the Standard Model could contribute. All measurements are consistent with the Standard Model predictions.

Keywords
Hadron-Hadron Scattering, Top physics
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-102789 (URN)10.1007/JHEP02(2014)107 (DOI)000332491600001 ()
Note

AuthorCount:2935;

Available from: 2014-04-23 Created: 2014-04-22 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bohm, C., Clément, C., Eriksson, D., . . . Yang, Z. (2014). Muon reconstruction efficiency and momentum resolution of the ATLAS experiment in proton-proton collisions at root s=7 TeV in 2010. European Physical Journal C, 74(9), Article ID 3034.
Open this publication in new window or tab >>Muon reconstruction efficiency and momentum resolution of the ATLAS experiment in proton-proton collisions at root s=7 TeV in 2010
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2014 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 74, no 9, article id 3034Article in journal (Refereed) Published
Abstract [en]

This paper presents a study of the performance of the muon reconstruction in the analysis of proton-proton collisions at root s = 7TeV at the LHC, recorded by the ATLAS detector in 2010. This performance is described in terms of reconstruction and isolation efficiencies and momentum resolutions for different classes of reconstructed muons. The results are obtained from an analysis of J/psi meson and Z boson decays to dimuons, reconstructed from a data sample corresponding to an integrated luminosity of 40 pb(-1). The measured performance is compared to Monte Carlo predictions and deviations from the predicted performance are discussed.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-115643 (URN)10.1140/epjc/s10052-014-3034-9 (DOI)000350141000001 ()
Note

AuthorCount:2926;

Available from: 2015-04-01 Created: 2015-03-27 Last updated: 2022-03-23Bibliographically approved
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