Direct photon production from viscous QGP

TL;DR

This paper simulates direct photon production in viscous quark-gluon plasma, highlighting the significant impact of viscosity on photon yields and establishing the reliable $p_T$ range for different viscosity levels.

Contribution

It provides a detailed simulation of photon production considering viscous effects, identifying the $p_T$ limits for reliable calculations at different viscosity parameters.

Findings

Viscous effects strongly influence photon production.

Reliable photon calculations are limited to specific $p_T$ ranges depending on viscosity.

Lower viscosity extends the reliable $p_T$ range for photon production.

Abstract

We simulate direct photon production in evolution of viscous QGP medium. Photons from Compton and annihilation processes are considered. Viscous effect on photon production is very strong and reliable simulation is possible only in a limited $p_T$ range. For minimally viscous fluid $\eta/s$=0.08), direct photons can be reliably computed only up to $p_T \leq$ 1.3 GeV. With reduced viscosity ($\eta/s$=0.04), the limit increases to $p_T \leq $2GeV.