Change search
Link to record
Permanent link

Direct link
Kim, Hyeon
Alternative names
Publications (10 of 360) Show all publications
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Tylmad, M. (2016). Centrality, rapidity, and transverse momentum dependence of isolated prompt photon production in lead-lead collisions at root S-NN=2.76 TeV measured with the ATLAS detector. Physical Review C, 93(3), Article ID 034914.
Open this publication in new window or tab >>Centrality, rapidity, and transverse momentum dependence of isolated prompt photon production in lead-lead collisions at root S-NN=2.76 TeV measured with the ATLAS detector
Show others...
2016 (English)In: Physical Review C, ISSN 2469-9985, Vol. 93, no 3, article id 034914Article in journal (Refereed) Published
Abstract [en]

Prompt photon production in root S-NN = 2.76-TeV Pb + Pb collisions has been measured by the ATLAS experiment at the Large Hadron Collider using data collected in 2011 with an integrated luminosity of 0.14 nb(-1). Inclusive photon yields, scaled by the mean nuclear thickness function, are presented as a function of collision centrality and transverse momentum in two pseudorapidity intervals, vertical bar eta vertical bar < 1.37 and 1.52 <= vertical bar eta vertical bar < 2.37. The scaled yields in the two pseudorapidity intervals, as well as the ratios of the forward yields to those at midrapidity, are compared to the expectations from next-to-leading-order perturbative QCD (pQCD) calculations. The measured cross sections agree well with the predictions for proton-proton collisions within statistical and systematic uncertainties. Both the yields and the ratios are also compared to two other pQCD calculations, one which uses the isospin content appropriate to colliding lead nuclei and another which includes nuclear modifications to the nucleon parton distribution functions.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-130143 (URN)10.1103/PhysRevC.93.034914 (DOI)000372800000003 ()
Available from: 2016-05-17 Created: 2016-05-09 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Erratum to: ATLAS Run 1 searches for direct pair production of third-generation squarks at the Large Hadron Collider (vol 75, 510, 2015). European Physical Journal C, 76(3), Article ID 153.
Open this publication in new window or tab >>Erratum to: ATLAS Run 1 searches for direct pair production of third-generation squarks at the Large Hadron Collider (vol 75, 510, 2015)
Show others...
2016 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, no 3, article id 153Article in journal (Other academic) Published
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-144443 (URN)10.1140/epjc/s10052-016-3935-x (DOI)000375303400004 ()2-s2.0-84962613211 (Scopus ID)
Note

Correction.

Available from: 2017-06-20 Created: 2017-06-20 Last updated: 2022-10-17Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Measurement of D-*+/-, D-+/- and D-S(+/-) meson production cross sections in pp collisions at root s=7 TeV with the ATLAS detector. Nuclear Physics B, 907, 717-763
Open this publication in new window or tab >>Measurement of D-*+/-, D-+/- and D-S(+/-) meson production cross sections in pp collisions at root s=7 TeV with the ATLAS detector
Show others...
2016 (English)In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 907, p. 717-763Article in journal (Refereed) Published
Abstract [en]

The production of D*(+/-), D-+/- and D-S(+/-) charmed mesons has been measured with the ATLAS detector in pp collisions at,/7s = 7 TeV at the LHC, using data corresponding to an integrated luminosity of 280 nb(-)1(.) The charmed mesons have been reconstructed in the range of transverse momentum 3.5 < p(T)(D) < 100 GeV and pseudorapidity vertical bar eta(D)vertical bar < 2.1. The differential cross sections as a function of transverse momentum and pseudorapidity were measured for D*(+/-) and D-+/- production. The next-to-leading-order QCD predictions are consistent with the data in the visible kinematic region within the large theoretical uncertainties. Using the visible D cross sections and an extrapolation to the full kinematic phase space, the strangeness -suppression factor in charm fragmentation, the fraction of charged non -strange D mesons produced in a vector state, and the total cross section of charm production at root s = 7 TeV were derived.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-131936 (URN)10.1016/j.nuclphysb.2016.04.032 (DOI)000376818000030 ()
Available from: 2016-07-05 Created: 2016-07-04 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åsman, B., Bendtz, K., Bessidskaia Bylund, O., Bohm, C., Clément, C., . . . Tylmad, M. (2016). Measurement of the centrality dependence of the charged-particle pseudorapidity distribution in proton-lead collisions at root s(NN)=5.02 TeV with the ATLAS detector. European Physical Journal C, 76(4), Article ID 199.
Open this publication in new window or tab >>Measurement of the centrality dependence of the charged-particle pseudorapidity distribution in proton-lead collisions at root s(NN)=5.02 TeV with the ATLAS detector
Show others...
2016 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, no 4, article id 199Article in journal (Refereed) Published
Abstract [en]

The centrality dependence of the mean charged-particle multiplicity as a function of pseudorapidity is measured in approximately 1 mu b(-1) of proton-lead collisions at a nucleon-nucleon centre-of-mass energy of root s(NN) = 5.02 TeV using the ATLAS detector at the Large Hadron Collider. Charged particles with absolute pseudorapidity less than 2.7 are reconstructed using the ATLAS pixel detector. The p + Pb collision centrality is characterised by the total transverse energy measured in the Pb-going direction of the forward calorimeter. The charged-particle pseudorapidity distributions are found to vary strongly with centrality, with an increasing asymmetry between the proton-going and Pb-going directions as the collisions become more central. Three different estimations of the number of nucleons participating in the p + Pb collision have been carried out using the Glauber model as well as two Glauber-Gribov inspired extensions to the Glauber model. Charged-particle multiplicities per participant pair are found to vary differently for these three models, highlighting the importance of including colour fluctuations in nucleon-nucleon collisions in the modelling of the initial state of p + Pb collisions.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-130878 (URN)10.1140/epjc/s10052-016-4002-3 (DOI)000375306400002 ()
Available from: 2016-06-07 Created: 2016-06-07 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Measurement of the CP-violating phase phi(s) and the B-s(0) meson decay width difference with B-s(0) -> J/psi phi decays in ATLAS. Journal of High Energy Physics (JHEP) (8), Article ID 147.
Open this publication in new window or tab >>Measurement of the CP-violating phase phi(s) and the B-s(0) meson decay width difference with B-s(0) -> J/psi phi decays in ATLAS
Show others...
2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 8, article id 147Article in journal (Refereed) Published
Abstract [en]

A measurement of the B-s(0) decay parameters in the B-s(0) -> J/psi/phi channel using an integrated luminosity of 14.3 fb(-1) collected by the ATLAS detector from 8TeV pp collisions at the LHC is presented. The measured parameters include the CP-violating phase phi(s), the decay width Gamma(s) and the width di ff erence between the mass eigenstates Delta Gamma(s). The values measured for the physical parameters are statistically combined with those from 4.9 fb-1 of 7TeV data, leading to the following: phi(s) = -0.090 +/- 0.078 (stat.) +/- 0.041 (syst.) rad Delta Gamma s = 0.085 +/- 0.011 (stat.) +/- 0.007 (syst.) ps(-1) Gamma(s) = 0.675 +/- 0.003 (stat.) +/- 0.003 (syst:) ps(-1). In the analysis the parameter Delta Gamma(s) is constrained to be positive. Results for phi(s) and Delta Gamma(s) are also presented as 68% and 95% likelihood contours in the phi(s)-Delta Gamma(s) plane. Also measured in this decay channel are the transversity amplitudes and corresponding strong phases. All measurements are in agreement with the Standard Model predictions.

Keywords
B physics, CP violation, Flavor physics, Hadron-Hadron scattering (experiments)
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-140368 (URN)10.1007/JHEP08(2016)147 (DOI)000391784400001 ()
Available from: 2017-03-30 Created: 2017-03-30 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at root s=7 and 8 TeV in the ATLAS experiment. European Physical Journal C, 76(1), Article ID 6.
Open this publication in new window or tab >>Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at root s=7 and 8 TeV in the ATLAS experiment
Show others...
2016 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, no 1, article id 6Article in journal (Refereed) Published
Abstract [en]

Combined analyses of the Higgs boson production and decay rates as well as its coupling strengths to vector bosons and fermions are presented. The combinations include the results of the analyses of the H -> gamma gamma, ZZ*, WW*, Z gamma, b (b) over bar, tau tau and mu mu decay modes, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 fb(-1) at root s = 7 TeV and 20.3 fb(-1) at root s = 8 TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is 1.18(-0.14)(+0.15). The observed Higgs boson production and decay rates are interpreted in a leading-order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions on the Higgs boson width and on the Standard Model particle content in loop processes. The data are found to be compatible with the Standard Model expectations for a Higgs boson at a mass of 125.36 GeV for all models considered.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-128562 (URN)10.1140/epjc/s10052-015-3769-y (DOI)000370645100005 ()
Available from: 2016-06-17 Created: 2016-03-30 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Performance of b-jet identification in the ATLAS experiment. Journal of Instrumentation, 11, Article ID P04008.
Open this publication in new window or tab >>Performance of b-jet identification in the ATLAS experiment
Show others...
2016 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 11, article id P04008Article in journal (Refereed) Published
Abstract [en]

The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty.

Keywords
Large detector systems for particle and astroparticle physics, Large detector-systems performance, Pattern recognition, cluster finding, calibration and fitting methods, Performance of High Energy Physics Detectors
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-131565 (URN)10.1088/1748-0221/11/04/P04008 (DOI)000375746400027 ()
Available from: 2016-06-30 Created: 2016-06-21 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Performance of pile-up mitigation techniques for jets in pp collisions at root s=8 TeV using the ATLAS detector. European Physical Journal C, 76(11), Article ID 581.
Open this publication in new window or tab >>Performance of pile-up mitigation techniques for jets in pp collisions at root s=8 TeV using the ATLAS detector
Show others...
2016 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, no 11, article id 581Article in journal (Refereed) Published
Abstract [en]

The large rate of multiple simultaneous protonproton interactions, or pile-up, generated by the Large Hadron Collider in Run 1 required the development of many new techniques to mitigate the adverse effects of these conditions. This paper describes the methods employed in the ATLAS experiment to correct for the impact of pile-up on jet energy and jet shapes, and for the presence of spurious additional jets, with a primary focus on the large 20.3 fb(-1) data sample collected at a centre-of-mass energy of root s = 8 TeV. The energy correction techniques that incorporate sophisticated estimates of the average pile-up energy density and tracking information are presented. Jet-to-vertex association techniques are discussed and projections of performance for the future are considered. Lastly, the extension of these techniques to mitigate the effect of pile-up on jet shapes using subtraction and grooming procedures is presented.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-143867 (URN)10.1140/epjc/s10052-016-4395-z (DOI)000399931300001 ()28316490 (PubMedID)
Available from: 2017-06-05 Created: 2017-06-05 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Åsman, B., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., . . . Ughetto, M. (2016). Study of the B-c(+) -> J/psi D-s(+) and Bc(+) -> J/psi D-s*(+) decays with the ATLAS detector. European Physical Journal C, 76(1), Article ID 4.
Open this publication in new window or tab >>Study of the B-c(+) -> J/psi D-s(+) and Bc(+) -> J/psi D-s*(+) decays with the ATLAS detector
Show others...
2016 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, no 1, article id 4Article in journal (Refereed) Published
Abstract [en]

The decays B-c(+) -> J/psi D-s(+) and B-c(+) -> J/psi D-s*(+) are studied with the ATLAS detector at the LHC using a dataset corresponding to integrated luminosities of 4.9 and 20.6 fb(-1) of pp collisions collected at centre-of-mass energies root s = 7 TeV and 8 TeV, respectively. Signal candidates are identified through J/psi -> mu(+)mu(-) and D-s(()*()+) -> phi pi(+)(gamma/pi(0)) decays. With a two-dimensional likelihood fit involving the B-c(+) reconstructed invariant mass and an angle between the mu(+) and D-s(+) candidate momenta in the muon pair rest frame, the yields of B-c(+) -> J/psi D-s(+) and B-c(+) -> J/psi D-s*(+), and the transverse polarisation fraction in B-c(+) -> J/psi D-s*(+) decay are measured. The transverse polarisation fraction is determined to be Gamma +/-+/-(B-c(+) -> J/psi D-s*(+))/Gamma(B-c(+) -> J/psi D-s*(+)) = 0.38 +/- 0.23 +/- 0.07, and the derived ratio of the branching fractions of the two modes is B-Bc+ -> J/psi D-s*+/B-Bc+ -> J/psi D-s(+) = 2.8(-0.8)(+1.2) +/- 0.3, where the first error is statistical and the second is systematic. Finally, a sample of B-c(+) -> J/psi pi(+) decays is used to derive the ratios of branching fractions B-Bc+ -> J/psi D-s*+/B-Bc+ -> J/psi pi(+) = 3.8 +/- 1.1 +/- 0.4 +/- 0.2 and B-Bc+ -> J/psi D-s*+/B-Bc+ -> J/psi pi(+) = 10.4 +/- 3.1 +/- 1.5 +/- 0.6, where the third error corresponds to the uncertainty of the branching fraction of D-s(+) -> phi(K+ K-)pi(+) decay. The available theoretical predictions are generally consistent with the measurement.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-128563 (URN)10.1140/epjc/s10052-015-3743-8 (DOI)000370645100003 ()
Available from: 2016-06-17 Created: 2016-03-30 Last updated: 2022-03-23Bibliographically approved
Abdallah, J., Alexa, C., Amaral Coutinho, Y., Amor Dos Santos, S. P., Anderson, K. J., Arabidze, G., . . . van Woerden, M. C. (2016). The Laser calibration of the ATLAS Tile Calorimeter during the LHC run 1. Journal of Instrumentation, 11, Article ID T10005.
Open this publication in new window or tab >>The Laser calibration of the ATLAS Tile Calorimeter during the LHC run 1
Show others...
2016 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 11, article id T10005Article in journal (Refereed) Published
Abstract [en]

This article describes the Laser calibration system of the ATLAS hadronic Tile Calorimeter that has been used during the run 1 of the LHC. First, the stability of the system associated readout electronics is studied. It is found to be stable with variations smaller than 0.6 %. Then, the method developed to compute the calibration constants, to correct for the variations of the gain of the calorimeter photomultipliers, is described. These constants were determined with a statistical uncertainty of 0.3 % and a systematic uncertainty of 0.2 % for the central part of the calorimeter and 0.5 % for the end-caps. Finally, the detection and correction of timing mis-configuration of the Tile Calorimeter using the Laser system are also presented.

Keywords
Detector alignment and calibration methods (lasers, sources, particle-beams), Calorimeters, Performance of High Energy Physics Detectors
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-136932 (URN)10.1088/1748-0221/11/10/T10005 (DOI)000387876400005 ()
Available from: 2016-12-30 Created: 2016-12-19 Last updated: 2022-03-23Bibliographically approved
Organisations

Search in DiVA

Show all publications