Large-scale magnetic fields from inflation due to Chern-Simons-like effective interaction

TL;DR

This paper proposes a mechanism during inflation where a Chern-Simons-like interaction with a fermion current can generate large-scale magnetic fields with strengths comparable to observed values, even at the Planck scale.

Contribution

It introduces a novel inflationary magnetogenesis model involving a dimension-six Chern-Simons-like interaction that can produce observable magnetic fields.

Findings

Magnetic fields of ~10^{-9} G on 1 Mpc scale can be generated.

The mechanism works even if the effective interaction scale is the Planck scale.

Large-scale magnetic fields are achievable through conformal invariance breaking during inflation.

Abstract

We discuss the generation of large-scale magnetic fields due to the breaking of the conformal invariance in the electromagnetic field through the $CPT$-even dimension-six Chern-Simons-like effective interaction with a fermion current in inflationary cosmology. It is shown that the magnetic fields on 1Mpc scale with the field strength of $\sim 10^{-9}$G at the present time can be generated even for the scale of the effective interaction being the Planck scale.