Model study of the energy dependence of the correlation between anisotropic flow and the mean transverse momentum in Au+Au collisions

Abstract

A hybrid model that employs the hadron-string transport model UrQMD and the (3+1)D relativistic viscous hydrodynamic code vHLLE, is used to investigate the beam energy dependence of the correlation coefficient $\rho (v_2^2,[p_T])$ between the average transverse momentum $[p_T]$ of hadrons emitted in an event and the square of the anisotropic flow coefficient $v_2^2$. For Au+Au collisions, the model predicts characteristic patterns for the energy and event-shape dependence of the variances for $[p_T]$ and $v_n^2$ ($\mathrm{Var}([p_T])$ and $\mathrm{Var}(v_2^2)$), and the covariance of $v_n^2$ and $[p_T]$ ($\mathrm{cov}(v_2^2,[p_T])$), consistent with the attenuation effects of the specific shear viscosity $\eta /s$. In contrast, $\rho (v_2^2,[p_T])$ is predicted to be insensitive to the beam energy but sensitive to the initial-state geometry of the collisions. These observations suggest that a precise set of measurements for $\mathrm{Var}([p_T])$, $\mathrm{Var}(v_2^2)$, $\mathrm{cov}(v_2^2,[p_T])$ and $\rho (v_2^2,[p_T])$ as a function of beam-energy and event-shape, could aid precision extraction of the temperature and baryon chemical-potential dependence of $\eta /s$ from the wealth of Au+Au data obtained in the RHIC beam energy scan.

Comments: 6 pages, 6 figures, submitted for publication