Anisotropic flow in Xe-Xe collisions at $\mathbf{\sqrt{s_{\rm{NN}}} = 5.44}$ TeV

TL;DR

This paper reports the first measurements of anisotropic flow coefficients in Xe-Xe collisions at 5.44 TeV, comparing them to Pb-Pb collisions, and discusses implications for initial state geometry and medium response.

Contribution

It provides novel measurements of flow coefficients in Xe-Xe collisions and compares them to Pb-Pb data, testing hydrodynamic models and initial state assumptions.

Findings

$v_2$ is suppressed in mid-central Xe-Xe compared to Pb-Pb.

$v_3$ is generally larger in Xe-Xe than in Pb-Pb.

Flow coefficients scale with transverse density, with some deviations.

Abstract

The first measurements of anisotropic flow coefficients $v_{\rm{n}}$ for mid-rapidity charged particles in Xe-Xe collisions at $\sqrt{s_{\rm{NN}}} = 5.44$ TeV are presented. Comparing these measurements to those from Pb-Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV, $v_{2}$ is found to be suppressed for mid-central collisions at the same centrality, and enhanced for central collisions. The values of $v_{3}$ are generally larger in Xe-Xe than in Pb-Pb at a given centrality. These observations are consistent with expectations from hydrodynamic predictions. When both $v_{2}$ and $v_{3}$ are divided by their corresponding eccentricities for a variety of initial state models, they generally scale with transverse density when comparing Xe-Xe and Pb-Pb, with some deviations observed in central Xe-Xe and Pb-Pb collisions. These results assist in placing strong constraints on both the initial state geometry and medium response for relativistic heavy-ion collisions.