Transport properties of a charged hot spot in an external electromagnetic field

TL;DR

This paper studies how a charged, rotating hot spot's transport properties, including viscosity, evolve under external electromagnetic perturbations, with implications for understanding viscosity-to-entropy ratios in lattice models.

Contribution

It introduces a perturbative framework to calculate the non-equilibrium distribution function and viscosity coefficients of a charged hot spot under external electromagnetic influence.

Findings

Viscosity coefficients depend on initial angular velocity and external field strength.

Distribution function calculated to first order in perturbation.

Results relate to viscosity-to-entropy ratio in lattice models.

Abstract

We investigate adiabatic expansion of a charged and rotating fluid element consisting of weakly interacting particles, which is initially perturbed by an external electromagnetic field. A framework for the perturbative calculation of the non-equilibrium distribution function of this fluid volume is considered and the distribution function is calculated to the first order in the perturbative expansion. This distribution function, which describes the evolution of the element with constant entropy, allows to calculate momentum flux tensor and viscosity coefficients of the expanding system. We show, that these viscosity coefficients depend on the initial angular velocity of the spot and on the strength of its initial perturbation by the external field. Obtained results are applied to the phenomenology of the viscosity to the entropy ratio calculated in lattice models.