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

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.

Comments: 8 pages, 4 figures. Proceedings of the 5th International Workshop on Astronomy and Relativistic Astrophysics (IWARA2011); João Pessoa, Brazil, 9-11 October 2011. v2: typos corrected