Viable requirements of curvature coupling helical magnetogenesis scenario

TL;DR

This paper evaluates the viability of a curvature coupling helical magnetogenesis model by checking its consistency with perturbative quantum field theory predictions and Planck data on curvature perturbations, finding a compatible parameter range.

Contribution

It provides a detailed analysis of the model's consistency with quantum field theory and observational data, establishing the conditions for its viability.

Findings

Model predicts sufficient large-scale magnetic fields.

Generated curvature perturbation is consistent with Planck data.

Parameter range supports both magnetic strength and observational constraints.

Abstract

In the present work, we examine the following points in the context of the recently proposed curvature coupling helical magnetogenesis scenario \cite{Bamba:2021wyx} -- (1) whether the model is consistent with the predictions of perturbative quantum field theory (QFT), and (2) whether the curvature perturbation induced by the generated electromagnetic (EM) field during inflation is consistent with the Planck data. Such requirements are well motivated in order to argue the viability of the magnetogenesis model under consideration. Actually, the magnetogenesis scenario proposed in \cite{Bamba:2021wyx} seems to predict sufficient magnetic strength over the large scales and also leads to the correct baryon asymmetry of the universe for a suitable range of the model parameter. However in the realm of inflationary magnetogenesis, these requirements are not enough to argue the viability of the model, particularly one needs to examine some more important requirements in this regard. We may recall that the calculations generally used to determine the magnetic field's power spectrum are based on the perturbative QFT -- therefore it is important to examine whether the predictions of such perturbative QFT are consistent with the observational bounds of the model parameter. On other hand, the generated gauge field acts as a source of the curvature perturbation which needs to be suppressed compared to that of contributed from the inflaton field in order to be consistent with the Planck observation. These set our motivation. Interestingly, both the aforementioned requirements in the context of the curvature coupling helical magnetogenesis scenario are found to be simultaneously satisfied by that range of the model parameter which leads to the correct magnetic strength over the large scale modes.