Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC

G. Aad; T. Abajyan; B. Abbott; J. Abdallah; S.A. Khalek; Mogens Dam; Jørgen Beck Hansen; Peter Henrik Hansen; Jørn Dines Hansen; John Renner Hansen; Simon Johann Franz Heisterkamp; Morten Dam Jørgensen; Sascha Mehlhase; Nele Maria Philomena Boelaert; Esben Bryndt Klinkby; Ask Emil Løvschall-Jensen; Björn Stefan Nilsson; Troels Christian Petersen; Stefania Xella

doi:10.1007/JHEP11(2013)183

Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC

G. Aad, T. Abajyan, B. Abbott, J. Abdallah, S.A. Khalek, Mogens Dam, Jørgen Beck Hansen, Peter Henrik Hansen, Jørn Dines Hansen, John Renner Hansen, Simon Johann Franz Heisterkamp, Morten Dam Jørgensen, Sascha Mehlhase, Nele Maria Philomena Boelaert, Esben Bryndt Klinkby, Ask Emil Løvschall-Jensen, Björn Stefan Nilsson, Troels Christian Petersen, Stefania Xella

Experimental Particle Physics

116 Citations (Scopus)

Abstract

The distributions of event-by-event harmonic flow coefficients υ_n for n = 2-4 are measured in √s_NN = 2.76TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb-1 recorded in 2010. The shapes of the υ_n distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for υ₂ and over most of the measured centrality range for υ₃ and υ₄. Significant deviations from this function are observed for υ₂ in mid-central and peripheral collisions, and a small deviation is observed for υ₃ in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The υ_n distributions are also measured independently for charged particles with 0.5 < p_T < 1 GeV and p_T > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two p_T ranges. The υ_n distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. Copyright CERN.

Original language	English
Article number	183
Journal	Journal of High Energy Physics (Online)
Volume	2013
Issue number	11
ISSN	1126-6708
DOIs	https://doi.org/10.1007/JHEP11(2013)183
Publication status	Published - 1 Nov 2013

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Aad, G., Abajyan, T., Abbott, B., Abdallah, J., Khalek, S. A., Dam, M., Hansen, J. B., Hansen, P. H., Hansen, J. D., Hansen, J. R., Heisterkamp, S. J. F., Jørgensen, M. D., Mehlhase, S., Boelaert, N. M. P., Klinkby, E. B., Løvschall-Jensen, A. E., Nilsson, B. S., Petersen, T. C., & Xella, S. (2013). Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC. Journal of High Energy Physics (Online), 2013(11), Article 183. https://doi.org/10.1007/JHEP11(2013)183

Aad, G, Abajyan, T, Abbott, B, Abdallah, J, Khalek, SA, Dam, M , Hansen, JB , Hansen, PH , Hansen, JD , Hansen, JR, Heisterkamp, SJF, Jørgensen, MD, Mehlhase, S, Boelaert, NMP, Klinkby, EB, Løvschall-Jensen, AE, Nilsson, BS, Petersen, TC & Xella, S 2013, 'Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC', Journal of High Energy Physics (Online), vol. 2013, no. 11, 183. https://doi.org/10.1007/JHEP11(2013)183

@article{58a5bd12dc344a169d9e0bd318a242f5,

title = "Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC",

abstract = "The distributions of event-by-event harmonic flow coefficients υn for n = 2-4 are measured in √sNN = 2.76TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb-1 recorded in 2010. The shapes of the υn distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for υ2 and over most of the measured centrality range for υ3 and υ4. Significant deviations from this function are observed for υ2 in mid-central and peripheral collisions, and a small deviation is observed for υ3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The υn distributions are also measured independently for charged particles with 0.5 < pT < 1 GeV and pT > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The υn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. Copyright CERN.",

author = "G. Aad and T. Abajyan and B. Abbott and J. Abdallah and S.A. Khalek and Mogens Dam and Hansen, {J{\o}rgen Beck} and Hansen, {Peter Henrik} and Hansen, {J{\o}rn Dines} and Hansen, {John Renner} and Heisterkamp, {Simon Johann Franz} and J{\o}rgensen, {Morten Dam} and Sascha Mehlhase and Boelaert, {Nele Maria Philomena} and Klinkby, {Esben Bryndt} and L{\o}vschall-Jensen, {Ask Emil} and Nilsson, {Bj{\"o}rn Stefan} and Petersen, {Troels Christian} and Stefania Xella",

year = "2013",

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doi = "10.1007/JHEP11(2013)183",

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T1 - Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC

AU - Aad, G.

AU - Abajyan, T.

AU - Abbott, B.

AU - Abdallah, J.

AU - Khalek, S.A.

AU - Dam, Mogens

AU - Hansen, Jørgen Beck

AU - Hansen, Peter Henrik

AU - Hansen, Jørn Dines

AU - Hansen, John Renner

AU - Heisterkamp, Simon Johann Franz

AU - Jørgensen, Morten Dam

AU - Mehlhase, Sascha

AU - Boelaert, Nele Maria Philomena

AU - Klinkby, Esben Bryndt

AU - Løvschall-Jensen, Ask Emil

AU - Nilsson, Björn Stefan

AU - Petersen, Troels Christian

AU - Xella, Stefania

PY - 2013/11/1

Y1 - 2013/11/1

N2 - The distributions of event-by-event harmonic flow coefficients υn for n = 2-4 are measured in √sNN = 2.76TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb-1 recorded in 2010. The shapes of the υn distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for υ2 and over most of the measured centrality range for υ3 and υ4. Significant deviations from this function are observed for υ2 in mid-central and peripheral collisions, and a small deviation is observed for υ3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The υn distributions are also measured independently for charged particles with 0.5 < pT < 1 GeV and pT > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The υn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. Copyright CERN.

AB - The distributions of event-by-event harmonic flow coefficients υn for n = 2-4 are measured in √sNN = 2.76TeV Pb+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum pT > 0.5GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb-1 recorded in 2010. The shapes of the υn distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for υ2 and over most of the measured centrality range for υ3 and υ4. Significant deviations from this function are observed for υ2 in mid-central and peripheral collisions, and a small deviation is observed for υ3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The υn distributions are also measured independently for charged particles with 0.5 < pT < 1 GeV and pT > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two pT ranges. The υn distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range. Copyright CERN.

U2 - 10.1007/JHEP11(2013)183

DO - 10.1007/JHEP11(2013)183

M3 - Journal article

SN - 1126-6708

VL - 2013

JO - Journal of High Energy Physics (Online)

JF - Journal of High Energy Physics (Online)

IS - 11

M1 - 183

ER -

Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector at the LHC

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