May 13 – 19, 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

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

May 15, 2018, 11:30 AM
Sala Mosaici-1, 3rd Floor (Palazzo del Casinò)

Sala Mosaici-1, 3rd Floor

Palazzo del Casinò

Parallel Talk Collective dynamics Collective dynamics


Tomasz Bold (AGH Univ. of Science and Technology, Krakow)


The experimental data collected by the ATLAS experiment during the 2015 Pb+Pb and 2017 Xe+Xe LHC runs offer new opportunities to study charged particle azimuthal anisotropy. The high-statistics Pb+Pb sample allows for a detailed study of the azimuthal anisotropy of produced particles. This should improve the understanding of initial conditions of nuclear collisions, hydrodynamical behavior of quark-gluon plasma and parton energy loss. New ATLAS measurements of differential and global Fourier harmonics of charged particles ($v_n$) in 5.02 TeV Pb+Pb and 5.44 TeV Xe+Xe collisions in a wide range of transverse momenta, pseudorapidity ($|\eta|<2.5$) and collision centrality are presented. The higher order harmonics, sensitive to fluctuations in the initial state, are measured up to $n=7$ using the two-particle correlation, cumulant and scalar product methods. The dynamic properties of QGP are studied using a recently-proposed modified Pearson's correlation coefficient, $\rho(v_n^2,p_\mathrm{T})$, between the eventwise mean transverse momentum and the magnitude of the flow vector in 5.02 TeV Pb+Pb and $p$+Pb collisions. Several important observations are made. The elliptic and triangular flow harmonics show an interesting universal $p_\mathrm{T}$-scaling. A linear correlation between the $v_2$ and $v_3$ coefficients at low and high $p_\mathrm{T}$ ranges is observed and quantified. The Pearson's correlation coefficient $\rho(v_2^2)$ is found to be negative in peripheral and positive in central Pb+Pb collisions. The value of $\rho(v_3^2)$ is found to be much smaller than $\rho(v_2^2)$ and to have similar centrality behavior as $\rho(v_2^2)$.

Centralised submission by Collaboration Presenter name already specified
Collaboration ATLAS
Content type Experiment

Primary author

Barbara Krystyna Wosiek (Institute of Nuclear Physics Polish Academy of Sciences (PL))

Presentation materials