The Chern-Simons diffusion rate in strongly coupled N=4 SYM plasma in an external magnetic field

TL;DR

This paper computes the Chern-Simons diffusion rate in a strongly coupled N=4 SYM plasma under an external magnetic field using holography, revealing how magnetic fields influence topological charge dynamics.

Contribution

It provides analytic results for the diffusion rate in both weak and strong magnetic field regimes, highlighting the magnetic field's impact on strongly coupled plasma dynamics.

Findings

Diffusion rate increases with magnetic field strength.

In strong fields, the rate scales as B×T^2.

Magnetic field induces dynamical dimensional reduction.

Abstract

We calculate the Chern-Simons diffusion rate in a strongly coupled N=4 SUSY Yang-Mills plasma in the presence of a constant external $U(1)_R$ magnetic flux via the holographic correspondence. Due to the strong interactions between the charged fields and non-Abelian gauge fields, the external Abelian magnetic field affects the thermal Yang-Mills dynamics and increases the diffusion rate, regardless of its strength. We obtain the analytic results for the Chern-Simons diffusion rate both in the weak and strong magnetic field limits. In the latter limit, we show that the diffusion rate scales as $B\times T^2$ and this can be understood as a result of a dynamical dimensional reduction.