Azimuthal anisotropy measurement of (multi-)strange hadrons in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 54.4 GeV

Abstract

Azimuthal anisotropy of produced particles is one of the most important observables used to access the collective properties of the expanding medium created in relativistic heavy-ion collisions. In this paper, we present second ($v_2$) and third ($v_3$) order azimuthal anisotropies of $K_S^0$, $\ddot{I}•$, $\hat{I}›$, $\hat{I}ž$ and $\hat{I}\text{c◯}$ at mid-rapidity ($|y|<$1) in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 54.4 GeV measured by the STAR detector. The $v_2$ and $v_3$ are measured as a function of transverse momentum and centrality. Their energy dependence is also studied. $v_3$ is found to be more sensitive to the change in the center-of-mass energy than $v_2$. Scaling by constituent quark number is found to hold for $v_2$ within 10%. This observation could be evidence for the development of partonic collectivity in 54.4 GeV Au+Au collisions. Differences in $v_2$ and $v_3$ between baryons and anti-baryons are presented, and ratios of $v_3$/$v_2^{3/2}$ are studied and motivated by hydrodynamical calculations. The ratio of $v_2$ of $\ddot{I}•$ mesons to that of anti-protons ($v_2(\ddot{I}•)/v_2(\bar{p})$) shows centrality dependence at low transverse momentum, presumably resulting from the larger effects from hadronic interactions on anti-proton $v_2$.

12 pages, 14 figures