Inflationary magnetogenesis with a self-consistent coupling function

TL;DR

This paper investigates inflationary magnetogenesis with a self-consistent coupling function, deriving constraints on the function, analyzing its form in large-field inflation, and discussing the strong coupling problem during slow-roll inflation.

Contribution

It introduces a self-consistent approach to the coupling function in inflationary magnetogenesis, deriving restrictive equations and analyzing its model dependence and evolution.

Findings

Coupling function depends on the inflaton potential.

Derived specific form of the coupling function in a simple model.

Identified the increasing nature of the coupling function during slow-roll inflation.

Abstract

In this paper, we discuss the inflationary magnetogenesis scenario, in which the coupling function is introduced to break the conformal invariance of electromagnetic action. Unlike in conventional models, we deduce the Maxwell's equations under the perturbed FRW metric. We found that, the self-consistency of the action depends on the form of the coupling function when the scalar mode perturbations have been considered. Therefore, this self-consistency can be seen as a restriction on the coupling function. In this paper, we give the restrictive equation for coupling function then obtain the specific form of the coupling function in a simple model. We found that the coupling function depends on the potential of the inflaton and thus is model dependent. We obtain the power spectrum of electric field and magnetic field in large-field inflation model. We also found that the coupling function is a incresing function of time during slow-roll era as most of inflationary magnetogenesis models, it will lead to strong coupling problem. This issue is discussed qualitatively by introducing a correction function during the preheating.