PHENIX Measurements of Higher-order Flow Harmonics for Identified Charged Hadrons in Au+Au collisions at $\sqrt{s_{NN}}=39-200$ GeV

TL;DR

This paper reports measurements of higher-order flow harmonics for identified charged hadrons in Au+Au collisions across a range of energies, revealing consistent scaling behaviors and stronger flow at higher energies, informing properties of the quark-gluon plasma.

Contribution

It provides detailed measurements of flow harmonics and their scaling in heavy-ion collisions over a broad energy range, offering new insights into collective behavior and viscosity.

Findings

Flow harmonics show little energy dependence.

Constituent quark number scaling holds over broad KE_T range.

Stronger flow observed at LHC compared to RHIC.

Abstract

The azimuthal anisotropy coefficients $v_{2,3,4}$, characterizing collective flow in Au+Au collisions, are presented for identified particle species as a function of transverse momentum ($p_T$), centrality ($\rm{cent}$) and beam collision energy ($\sqrt{s_{NN}}=0.039-0.20$ TeV). The $v_n$ values for each particle species, show little, if any, change over the measured beam energy range, and ${v_n}/{(n_q)^{n/2}}$ vs. $KE_T/n_q$ scales to a single curve (constituent quark number ($n_q)$ scaling) for each $n$, over a broad range of transverse kinetic energies ($KE_T$). A comparison of $v_2(p_T)$ for individual particle species obtained in Au+Au collisions at $\sqrt{s_{NN}}=0.20$ TeV (RHIC) and Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV (LHC), indicate stronger collective flow at the LHC. These flow measurements and their scaling patterns, can provide important additional constraints for extraction of the specific viscosity $\eta/s$.