$\eta(T)/s (T)$ and collective flow in chiral hydrodynamics

TL;DR

This paper investigates how the temperature dependence of shear viscosity to entropy density ratio ($ta/s$) and chiral field dynamics influence the elliptic flow ($v_2$) in heavy-ion collision simulations using conformal hydrodynamics.

Contribution

It introduces a study of chiral field effects on hydrodynamic evolution and assesses the impact of temperature-dependent $ta/s$ on elliptic flow in heavy-ion collisions.

Findings

Elliptic flow $v_2$ is minimally affected by chiral field coupling.

Temperature dependence of $ta/s$ significantly influences $v_2$.

Chiral fields have limited impact on the collective flow observables.

Abstract

Using relativistic conformal hydrodynamics coupled to the linear $\sigma$ model we study the evolution of matter created in heavy--ion collisions. We focus the study on the influence of the dynamics of the chiral fields on the charged-hadron elliptic flow $v_2$ for a temperature--independent as well as for a temperature--dependent $\eta/s$ that is calculated from kinetic theory. We find that $v_2$ is not very sensitive to the coupling of chiral fields to the hydrodynamic evolution, but the temperature dependence of $\eta/s$ plays a much bigger role on this observable.