Anomalous Magnetohydrodynamics

TL;DR

This paper investigates the behavior of anomalous currents in magnetohydrodynamics, especially their persistence at high conductivities, and explores the implications for magnetic configurations and solutions in the context of the electroweak plasma.

Contribution

It provides a detailed analysis of anomalous currents in magnetohydrodynamics, extending hydromagnetic solutions to include anomalies and examining covariant aspects in conformally flat geometries.

Findings

Anomalous currents can persist in highly conductive plasmas.

Magnetic configurations minimizing energy with conserved helicity align with ideal MHD solutions.

Hydromagnetic solutions with finite gyrotropy can be extended to anomalous MHD.

Abstract

Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy with charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved coincide, in the perfectly conducting limit, with the ones obtainable in ideal magnetohydrodynamics where the anomalous currents are neglected. It is argued that this is the rationale for the ability of extending to anomalous magnetohydrodynamics the hydromagnetic solutions characterized by finite gyrotropy. The generally covariant aspects of the problem are addressed with particular attention to conformally flat geometries which are potentially relevant for the description of the electroweak plasma prior to the phase transition.