Shear viscosity, cavitation and hydrodynamics at LHC

TL;DR

This paper investigates how cavitation affects the validity of relativistic viscous hydrodynamics in quark-gluon plasma evolution at LHC, highlighting the impact of shear viscosity and conformal terms.

Contribution

It demonstrates that cavitation occurs early in hydrodynamic evolution due to high shear viscosity, challenging the applicability of hydrodynamics in such conditions.

Findings

Cavitation occurs within 2 fm/c for LHC initial conditions.

High shear viscosity drives cavitation in the fluid.

Conformal terms influence the cavitation timing.

Abstract

We study evolution of quark-gluon matter in the ultrarelativistic heavy-ion collisions within the frame work of relativistic second-order viscous hydrodynamics. In particular, by using the various prescriptions of a temperature-dependent shear viscosity to the entropy ratio, we show that the hydrodynamic description of the relativistic fluid become invalid due to the phenomenon of cavitation. For most of the initial conditions relevant for LHC, the cavitation sets in very early during the evolution of the hydrodynamics in time $\lesssim 2 $fm/c. The cavitation in this case is entirely driven by the large values of shear viscosity. Moreover we also demonstrate that the conformal term used in equations of the relativistic dissipative hydrodynamic can influence the cavitation time.