Effects of Bulk Viscosity on $p_T$-Spectra and Elliptic Flow Parameter

TL;DR

This paper investigates how bulk viscosity influences particle spectra and elliptic flow in heavy-ion collisions, emphasizing the importance of considering both shear and bulk viscosity for accurate interpretation of experimental data.

Contribution

It introduces a method to estimate viscous effects on phase space distributions using Grad's fourteen moment approach in a multi-component system.

Findings

Bulk viscosity significantly affects particle spectra.

Viscous corrections alter elliptic flow coefficients.

Careful treatment of shear and bulk viscosity is necessary for data analysis.

Abstract

We estimate the effects of viscosity on the phase space distribution appearing in the Cooper-Frye formula within the framework of the Grad's fourteen moment method and find that there are non-trivialities in the discussion of a multi-component system. We calculate the viscous corrections of particle spectra and elliptic flow coefficients from the distortion of the distribution using the flow and the hypersurface taken from a (3+1)-dimensional ideal hydrodynamic simulation. We see that the bulk viscosity have visible effects on particle spectra. The results suggest we should treat both shear and bulk viscosity carefully when constraining the transport coefficients from experimental data.