Out-of-equilibrium photon production and electric conductivity in a holographic Bjorken expanding plasma

TL;DR

This paper analytically calculates out-of-equilibrium photon production and electric conductivity in a strongly coupled, expanding plasma using holography, revealing that early in expansion, rates are significantly higher and harder.

Contribution

It provides the first analytical holographic computation of out-of-equilibrium photon production and conductivity in an expanding plasma at late times.

Findings

Out-of-equilibrium photon production rates are higher early in expansion.

Electric conductivity is computed for a strongly coupled plasma.

Results are valid at late times when plasma follows Bjorken hydrodynamics.

Abstract

We analytically compute the out-of-equilibrium direct photon production rate and electric conductivity, in a strongly coupled and expanding Bjorken plasma, from holography. Our results are valid at late times where the expanding plasma asymptotes Bjorken hydrodynamics. The out-of-equilibrium rates are substantially harder and larger, early on in the Bjorken expansion phase.