CERN Accelerating science

ATLAS Slides
Report number ATL-PHYS-SLIDE-2020-184
Title ATLAS measurements of transverse and longitudinal flow fluctuations
Author(s) Behera, Arabinda (Stony Brook University)
Corporate author(s) The ATLAS collaboration
Collaboration ATLAS Collaboration
Submitted to 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, Austin (remote Only), Tx, Usa, 31 May - 5 Jun 2020
Submitted by arabinda.behera@cern.ch on 09 Jun 2020
Subject category Particle Physics - Experiment
Accelerator/Facility, Experiment CERN LHC ; ATLAS
Free keywords HEAVYIONS
Abstract ATLAS measurements of flow harmonics (vn) and their fluctuations in Pb+Pb and Xe+Xe collisions covering a wide range of transverse momenta, pseudorapidity and collision centrality are presented. The measurements are performed using data from Xe+Xe collisions at 5.44 TeV, Pb+Pb collisions at 5.02 TeV, and p+Pb collisions at 5.02 and 8.16 TeV. The vn are measured up to n=6 using the two-particle correlations, multi-particle cumulants, and scalar product methods. The vn values are also performed using a non-flow subtraction technique that was developed for flow measurements in pp and p+Pb collisions. This non-flow subtraction is found to have a significant effect on the measured vn at high-pT and in peripheral collisions. A universal scaling in the pT dependence of the vn is observed for both systems. Measurements of correlations between the vn for different order n, studied with three- and four-particle mixed-harmonic cumulants, are also presented, and contributions to these correlations from ``centrality fluctuations'' are also discussed. Measurements of longitudinal flow decorrelations involving two- and four-particle correlations for v2 and v3 in Xe+Xe and p+Pb collisions are also presented and compared with the corresponding measurements in Pb+Pb collisions. The four-particle decorrelation is found to not factorize as a product of two-particle decorrelations. The ability of such measurements to distinguish between different models of initial geometry and to reduce the uncertainty in determining the effective shear-viscosity to entropy-density ratio of the QGP is demonstrated.



 Record created 2020-06-09, last modified 2020-06-09


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