Centrality and transverse momentum dependence of elliptic flow of multi-strange hadrons and $\phi$ meson in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

TL;DR

This paper reports precise measurements of elliptic flow for multi-strange hadrons and $\phi$ mesons in Au+Au collisions at 200 GeV, revealing partonic collectivity and quark scaling behaviors.

Contribution

It provides new high-precision data on elliptic flow of strange hadrons, demonstrating quark-level collectivity and testing number of constituent quark scaling at top RHIC energy.

Findings

Strange hadrons show similar flow patterns to lighter particles, indicating strong strange quark flow.

Number of constituent quark scaling holds within uncertainties for different centralities.

Possible breakdown of mass ordering between $\phi$ and proton $v_{2}$ at low transverse momentum.

Abstract

We present high precision measurements of elliptic flow near midrapidity ($|y|<1.0$) for multi-strange hadrons and $\phi$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=$ 200 GeV. We observe that the transverse momentum dependence of $\phi$ and $\Omega$ $v_{2}$ is similar to that of $\pi$ and $p$, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30$\%$ and 30-80$\%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $\phi$ and proton $v_{2}$ at low transverse momentum in the 0-30$\%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$.