Probing the non-equilibrium dynamics of hot and dense QCD with dileptons

TL;DR

This paper demonstrates that thermal dileptons in heavy ion collisions serve as effective probes for the medium's transport properties and early-time dynamics, revealing sensitivities to shear viscosity and initial shear-stress conditions.

Contribution

It introduces the use of electromagnetic azimuthal momentum anisotropies as sensitive indicators of shear viscosity's temperature dependence and initial shear-stress in QCD medium.

Findings

Dileptons are sensitive to shear relaxation time.

Azimuthal anisotropies reveal temperature-dependent shear viscosity.

Results provide new insights into early-time QCD dynamics.

Abstract

It is argued that, in heavy ion collisions, thermal dileptons are good probes of the transport properties of the medium created in such events, and also of its early-time dynamics, usually inaccessible to hadronic observables. In this work we show that electromagnetic azimuthal momentum anisotropies do not only display a sensitivity to the shear relaxation time and to the initial shear-stress tensor profile, but also to the temperature dependence of the shear viscosity coefficient.