Bulk viscosity effects on elliptic flow

TL;DR

This paper investigates how bulk viscosity influences elliptic flow in heavy-ion collisions, revealing complex effects that depend on transverse momentum and are shaped by the equation of state and transport properties.

Contribution

It provides a detailed analysis of bulk viscosity effects on elliptic flow using realistic models, highlighting non-trivial momentum-dependent behavior.

Findings

Bulk viscosity reduces $v_{2}$ at low $p_{T}$ more than shear viscosity.

At high $p_{T}$, bulk viscosity enhances $v_{2}$ compared to ideal fluid.

The effects are driven by the interplay between the equation of state and transport coefficients.

Abstract

The effects of bulk viscosity on the elliptic flow $v_{2}$ are studied using realistic equation of state and realistic transport coefficients. We find that thebulk viscosity acts in a non trivial manner on $v_{2}$. At low $p_{T}$, the reduction of $v_{2}$ is even more effective compared to the case of shear viscosity, whereas at high $p_{T}$, an enhancement of $v_{2}$ compared to the ideal case is observed. We argue that this is caused by the competition of the critical behavior of the equation of state and the transport coefficients.