Diagnostics of plasma photoemission at strong coupling

TL;DR

This paper calculates the photon emission spectrum from a strongly coupled supersymmetric plasma using holography, revealing how the spectrum changes with coupling strength and aligning with weak-coupling expectations.

Contribution

It extends holographic photon emission calculations by including string theory corrections at finite coupling, providing new insights into the spectrum's dependence on the 't Hooft coupling.

Findings

Photon emission peak increases as coupling weakens

Maximal emission shifts to lower momentum with decreasing coupling

Total emitted photons increase at weaker coupling

Abstract

We compute the spectrum of photons emitted by the finite-temperature large-N SU(N) ${\cal {N}}=4$ supersymmetric Yang-Mills plasma coupled to electromagnetism, at strong yet finite 't Hooft coupling. We work in the holographic dual description, extended by the inclusion of the full set of ${\cal{O}}(\alpha'^3)$ type IIB string theory operators that correct the minimal supergravity action. We find that, as the t' Hooft coupling decreases, the peak of the spectrum increases, and the momentum of maximal emission shifts towards the infra-red, as expected from weak-coupling computations. The total number of emitted photons also increases as the 't Hooft coupling weakens.