Brighter Branes, enhancement of photon production by strong magnetic fields in the gauge/gravity correspondence

TL;DR

This paper uses gauge/gravity duality to study how strong magnetic fields enhance photon production in a quark-gluon plasma, revealing anisotropic effects consistent with heavy ion collision experiments.

Contribution

It constructs a family of back reacted geometries with strong magnetic fields to analyze photon production, including operator mixing effects, which is a novel approach.

Findings

Photon production is significantly enhanced by strong magnetic fields.

The enhancement shows anisotropy, especially at low momentum.

Results qualitatively agree with heavy ion collision experiments.

Abstract

We use the gauge/gravity correspondence to calculate the rate of photon production in a strongly coupled N=4 plasma in the presence of an intense magnetic field. We start by constructing a family of back reacted geometries that include the black D3-brane solution, as a smooth limiting case for B=0, and extends to backgrounds with an arbitrarily large constant magnetic field. This family provides the gravitational dual of a field theory in the presence of a very strong magnetic field which intensity can be fixed as desired and allows us to study its effect on the photon production of a quark-gluon plasma. The inclusion of perturbations in the electromagnetic field on these backgrounds is consistent only if the metric is perturbed as well, so we use methods developed to treat operator mixing to manage these general perturbations. Our results show a clear enhancement of photon production with a significant anisotropy, which, in qualitative agreement with the experiments of heavy ion collisions, is particularly noticeable for low P.