# Investigating the temperature dependence of the specific shear viscosity of QCD matter with dilepton radiation

## TL;DR

This paper explores how the temperature-dependent specific shear viscosity of QCD matter influences thermal dilepton production and flow in heavy-ion collisions, highlighting dileptons' potential to probe high-temperature viscosity.

## Contribution

It introduces a method to use thermal dileptons to determine the magnitude of shear viscosity at high temperatures in QCD matter.

## Key findings

- Elliptic flow of thermal dileptons can measure shear viscosity at high temperatures.
- Discriminating between different viscosity temperature dependencies is challenging at RHIC.
- Thermal dileptons are sensitive probes of QCD matter's viscous properties.

## Abstract

This work reports on investigations of the effects on the evolution of viscous hydrodynamics and on the flow coefficients of thermal dileptons, originating from a temperature-dependent specific shear viscosity $\eta/s (T)$ at temperatures beyond 180 MeV formed at the Relativistic Heavy-Ion Collider (RHIC). We show that the elliptic flow of thermal dileptons can resolve the magnitude of $\eta/s$ at the high temperatures, where partonic degrees of freedom become relevant, whereas discriminating between different specific functional forms will likely not be possible at RHIC using this observable.