Large-scale gauge spectra and pseudoscalar couplings

TL;DR

The paper investigates how gauge spectra and pseudoscalar interactions during inflation influence magnetic field generation and baryon asymmetry, finding that pseudoscalar effects mainly impact gyrotropic spectra relevant for baryogenesis.

Contribution

It introduces a new method for estimating gauge power spectra with pseudoscalar interactions and analyzes their effects across various inflationary models.

Findings

Pseudoscalar contributions have minimal impact on large-scale magnetic fields.

Parity-breaking terms significantly influence gyrotropic spectra related to baryogenesis.

Certain parameter regions produce sufficient baryon asymmetry and magnetic fields of a few hundredths of a nG.

Abstract

It is shown that the slopes of the superhorizon hypermagnetic spectra produced by the variation of the gauge couplings are practically unaffected by the relative strength of the parity-breaking terms. A new method is proposed for the estimate of the gauge power spectra in the presence of pseudoscalar interactions during inflation. To corroborate the general results, various concrete examples are explicitly analyzed. Since the large-scale gauge spectra also determine the late-time magnetic fields it turns out that the pseudoscalar contributions have little impact on the magnetogenesis requirement. Conversely the parity-breaking terms crucially affect the gyrotropic spectra that may seed, in certain models, the baryon asymmetry of the Universe. In the most interesting regions of the parameter space the modes reentering prior to symmetry breaking lead to a sufficiently large baryon asymmetry while the magnetic power spectra associated with the modes reentering after symmetry breaking may even be of the order of a few hundredths of a nG over typical length scales comparable with the Mpc prior to the collapse of the protogalaxy. From the viewpoint of the effective field theory description of magnetogenesis scenarios these considerations hold generically for the whole class of inflationary models where the inflaton is not constrained by any underlying symmetry.