Inflationary Magnetogenesis with Broken Local U(1) Symmetry

TL;DR

This paper proposes a model for inflationary magnetogenesis by breaking the local U(1) gauge symmetry during inflation, resulting in a nearly scale-invariant magnetic spectrum without strong coupling or back reaction issues.

Contribution

It introduces a novel approach to inflationary magnetogenesis by temporarily breaking the local U(1) symmetry, ensuring a consistent magnetic field generation.

Findings

Achieves an almost scale-invariant magnetic spectrum.

Electromagnetic contributions to curvature perturbations are negligible.

Restores U(1) symmetry at the end of inflation.

Abstract

We point out that a successful inflationary magnetogenesis could be realised if we break the local U(1) gauge symmetry during inflation. The effective electric charge is fixed as a fundamental constant, which allows us to obtain an almost scale invariant magnetic spectrum avoiding both the strong coupling and back reaction problems. We examine the corrections to the primordial curvature perturbation due to these stochastic electromagnetic fields and find that, at both linear and non-linear orders, the contributions from the electromagnetic field are negligible compared to those created from vacuum fluctuations. Finally, the U(1) gauge symmetry is restored at the end of inflation.