Development of relativistic shock waves in viscous gluon matter

TL;DR

This paper studies how relativistic shock waves form and behave in viscous gluon matter, showing that higher viscosity impedes shock development, with implications for ultrarelativistic heavy-ion collision modeling.

Contribution

It demonstrates the transition from ideal to viscous shock waves in gluon matter by varying shear viscosity, validated through microscopic and hydrodynamic simulations.

Findings

Viscous shock waves are suppressed at high shear viscosity to entropy density ratios.

An η/s ratio above 0.2 prevents well-defined shock wave formation.

Results are consistent across microscopic parton cascade and hydrodynamic models.

Abstract

To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio $\eta/s$. We show that an $\eta/s$ ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. These findings are confirmed by viscous hydrodynamic calculations.