A Blast Wave Model With Viscous Corrections

TL;DR

This paper enhances blast wave models for heavy ion collisions by incorporating shear viscous corrections, allowing for better data fitting and constraints on the hadron gas viscosity at freeze-out.

Contribution

It introduces shear viscous corrections into blast wave models, adding a new parameter for specific shear viscosity, and extracts this parameter from experimental data.

Findings

Shear viscosity $\,\eta/s$ is found to be small.

Viscous corrections improve the fit to experimental data.

Constraints on $\,\eta/s$ at freeze-out are obtained.

Abstract

Hadronic observables in the final stage of heavy ion collision can be described well by fluid dynamics or blast wave parameterizations. We improve existing blast wave models by adding shear viscous corrections to the particle distributions in the Navier-Stokes approximation. The specific shear viscosity $\eta/s$ of a hadron gas at the freeze-out temperature is a new parameter in this model. We extract the blast wave parameters with viscous corrections from experimental data which leads to constraints on the specific shear viscosity at kinetic freeze-out. Preliminary results show $\eta/s$ is rather small.