# 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions

May 31, 2020 to June 5, 2020
Online
US/Central timezone

## ATLAS measurements of transverse and longitudinal flow decorrelations in Xe+Xe, Pb+Pb, and $p$+Pb collisions

Jun 3, 2020, 10:30 AM
20m
https://cern.zoom.us/j/94475079687

#### https://cern.zoom.us/j/94475079687

Oral Presentation Initial State

### Speaker

Arabinda Behera (Stony Brook University (US))

### Description

ATLAS measurements of flow harmonics ($v_n$) 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 $v_{n}$ are measured up to $n=6$ using the two-particle correlations, multi-particle cumulants, and scalar product methods. The $v_{n}$ 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 $v_n$ at high-$p_T$ and in peripheral collisions. A universal scaling in the $p_{T}$ dependence of the $v_{n}$ is observed for both systems.
Measurements of correlations between the $v_n$ 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 $v_{2}$ and $v_{3}$ 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.

Contribution type Contributed Talk Initial State ATLAS

### Primary authors

Lidija Zivkovic (Institute of physics Belgrade (RS))

### Presentation materials

 HP20talk_ABehera_ver3.pdf Recording