Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at sNN−−−−√ = 2.76 TeV with the ATLAS detector at the LHC

Allison, Lee and Barton, Adam and Borissov, Guennadi and Bouhova-Thacker, Eva and Chilingarov, Alexandre and Dearnaley, William and Fox, Harald and Grimm, Kathryn and Henderson, Robert and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin and Love, Peter and Maddocks, Harvey and Smizanska, Maria and Walder, James (2013) Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at sNN−−−−√ = 2.76 TeV with the ATLAS detector at the LHC. Journal of High Energy Physics, 2013. ISSN 1029-8479

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The distributions of event-by-event harmonic flow coefficients v n for n = 2- 4 are measured in sNN−−−−√ = 2.76 TeV Pb + Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum p T > 0.5 GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb−1 recorded in 2010. The shapes of the v n distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for v 2 and over most of the measured centrality range for v 3 and v 4. Significant deviations from this function are observed for v 2 in mid-central and peripheral collisions, and a small deviation is observed for v 3 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 v 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 v 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.

Item Type: Journal Article
Journal or Publication Title: Journal of High Energy Physics
Additional Information: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/3100/3106
Departments: Faculty of Science and Technology > Physics
ID Code: 68344
Deposited By: ep_importer_pure
Deposited On: 24 Jan 2014 05:54
Refereed?: Yes
Published?: Published
Last Modified: 20 Feb 2020 01:56

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