# Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions

3-9 November 2019
Wanda Reign Wuhan Hotel
Asia/Shanghai timezone

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

5 Nov 2019, 08:40
20m
Ball Room 1 (Wanda Reign Wuhan Hotel)

### Ball Room 1

#### Wanda Reign Wuhan Hotel

Oral Presentation Collective dynamics and final state interaction

### Speaker

Soumya Mohapatra for the ATLAS Collaboration (Columbia 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 $v_{n}$ are measured up to $n=7$ using the two-particle correlations, multi-particle cumulants and scalar product methods.The $v_{n}$ for $n$=2-7 is obtained with various correlation methods, together with a non-flow subtraction technique to improve the understanding of flow in peripheral region.A universal scaling in the $p_{T}$ dependence of the $v_{n}$ is observed for both systems. For the first time, longitudinal flow decorrelations involving two- and four-particle correlations for $v_{2}$ and $v_{3}$ are measured in Xe+Xe collisions and compared with results from 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 are demonstrated.