# Scale-invariant Helical Magnetic Fields from Inflation

## TL;DR

This paper presents a model for generating large-scale, scale-invariant helical magnetic fields during inflation, achieving observable amplitudes without backreaction or strong coupling issues.

## Contribution

It introduces a novel inflationary magnetogenesis model that produces observable magnetic fields while addressing conductivity effects and avoiding common theoretical problems.

## Key findings

- Magnetic fields of about 10^{-15} G can be generated today.
- The model accounts for electric conductivity, terminating magnetogenesis before reheating.
- No backreaction or strong coupling problems occur in the proposed scenario.

## Abstract

We discuss a model which can generate scale-invariant helical magnetic fields on large scales ($\lesssim 1$Mpc) in the primordial universe. It is also shown that the electric conductivity becomes significant and terminates magnetogenesis even before reheating is completed. By solving the electromagnetic dynamics taking conductivity into account, we find that magnetic fields with amplitude $B\simeq 10^{-15}{\rm G}$ at present can be generated without encountering a backreaction or strong coupling problem.