Primordial Generation of Magnetic Fields

TL;DR

This paper revisits the primordial magnetic field generation at high temperatures using a modified kinetic theory that incorporates quantum anomalies, revealing the dominant role of collisional instabilities.

Contribution

It introduces a consistent kinetic theory framework accounting for quantum anomalies to analyze primordial magnetic field generation.

Findings

Qualitative agreement with previous heuristic results.

Identification of instabilities in collisional and collisionless regimes.

Collisional regime instability likely dominates.

Abstract

We reexamine generation of the primordial magnetic fields, at temperature $T>80$TeV, by applying a consistent kinetic theory framework which is suitably modified to take the quantum anomaly into account. The modified kinetic equation can reproduce the known quantum field theoretic results upto the leading orders. We show that our results qualitatively matches with the earlier results obtained using heuristic arguments. The modified kinetic theory can give the instabilities responsible for generation of the magnetic field due to chiral imbalance in two distinct regimes: a) when the collisions play a dominant role and b) when the primordial plasma can be regarded as collisionless. We argue that the instability developing in the collisional regime can dominate over the instability in the collisionless regime.