On Quantum Anomalous Effects in Electrodynamics of the Early Universe

TL;DR

This paper explores how quantum chiral anomalies influence electromagnetic field evolution in the early universe and dense astrophysical objects, revealing significant effects on magnetic field amplification, helicity creation, and turbulence dynamics.

Contribution

It introduces extended magnetohydrodynamic equations incorporating chiral effects, demonstrating their impact on magnetic field evolution and turbulence in high-temperature plasmas.

Findings

Chiral effects can exponentially amplify magnetic fields.

Magnetic helicity can be generated from non-helical initial fields.

Chiral anomalies support turbulent inverse cascades and faster correlation growth.

Abstract

This dissertation studies the quantum anomalous effects on the description of high energy electrodynamics. We argue that on the temperatures comparable to the electroweak scale, characteristic for the early Universe and objects like neutron stars, the description of electromagnetic fields in conductive plasmas needs to be extended to include the effects of chiral anomaly. It is demonstrated that chiral effects can have a significant influence on the evolution of magnetic fields, tending to produce exponential amplification, creation of magnetic helicity from initially non-helical fields, and can lead to an inverse energy transfer. We further discuss the modified magnetohydrodynamic equations around the electroweak transition. The obtained solutions demonstrate that the asymmetry between right-handed and left-handed charged fermions of negligible mass typically grows with time when approaching the electroweak crossover from higher temperatures, until it undergoes a fast decrease at the transition, and then eventually gets damped at lower temperatures in the broken phase. At the same time, the dissipation of magnetic fields gets slower due to the chiral effects. We furthermore report some first analytical attempts in the study of chiral magnetohydrodynamic turbulence. Using the analysis of simplified regimes and qualitative arguments, it is shown that anomalous effects can strongly support turbulent inverse cascade and lead to a faster growth of the correlation length, when compared to the evolution predicted by the non-chiral magnetohydrodynamics. Finally, the discussion of relaxation towards minimal energy states in the chiral magnetohydrodynamic turbulence is also presented.