Suppression of elliptic flow in a minimally viscous quark-gluon plasma

TL;DR

This paper demonstrates that even minimal shear viscosity significantly reduces elliptic flow in quark-gluon plasma, challenging previous ideal fluid assumptions in heavy-ion collision interpretations.

Contribution

It provides a detailed viscous hydrodynamic simulation showing the impact of minimal shear viscosity on elliptic flow evolution.

Findings

Minimal shear viscosity causes large elliptic flow suppression.

Viscous effects are significant even at the conjectured lower bound.

Results question the ideal fluid interpretation of RHIC data.

Abstract

We compute the time evolution of elliptic flow in non-central relativistic heavy-ion collisions, using a (2+1)-dimensional code with longitudinal boost-invariance to simulate viscous fluid dynamics in the causal Israel-Stewart formulation. We show that even ``minimal'' shear viscosity eta/s=hbar/(4pi) leads to a large reduction of elliptic flow compared to ideal fluid dynamics, raising questions about the interpretation of recent experimental data from the Relativistic Heavy Ion Collider.