Measurement of the azimuthal anisotropy of charged particles in 5.02 TeV Pb+Pb and 5.44 TeV Xe+Xe collisions with ATLAS experiment

Abstract

The high-statistics data collected by the ATLAS experiment during the 2015 Pb+Pb and 2017 Xe+Xe LHC runs are used to measure charged particle azimuthal anisotropy. The flow harmonics, v n (n=2-7), are obtained with the two-particle correlation, scalar-product and event-plane methods. Measurements of differential and global flow harmonics in Pb+Pb and Xe+Xe collisions in a wide range of transverse momenta (p T up to 60 GeV), pseudorapidity (|η| < 2.5) and collision centrality (0-80%) are presented. The higher order harmonics, sensitive to fluctuations in the initial state, are precisely measured. In this analysis the v 7 is obtained for the first time. The new flow results allow to improve the understanding of initial conditions of nuclear collisions, hydrodynamical behavior of the quark-gluon plasma and the parton energy loss.