Large-scale magnetic fields, non-Gaussianity, and gravitational waves from inflation

TL;DR

This paper investigates how inflationary models with coupled scalar and pseudoscalar fields can generate large-scale magnetic fields, non-Gaussianity, and gravitational waves, aligning with recent observational data.

Contribution

It introduces a model where hypercharge fields couple to multiple fields, breaking conformal invariance and producing observable cosmological signatures.

Findings

Magnetic fields on the Hubble horizon are consistent with observations.

Local non-Gaussianity levels match Planck data.

Tensor-to-scalar ratio aligns with recent measurements.

Abstract

We explore the generation of large-scale magnetic fields in the so-called moduli inflation. The hypercharge electromagnetic fields couple to not only a scalar field but also a pseudoscalar one, so that the conformal invariance of the hypercharge electromagnetic fields can be broken. We explicitly analyze the strength of the magnetic fields on the Hubble horizon scale at the present time, the local non-Gaussianity of the curvature perturbations originating from the massive gauge fields, and the tensor-to-scalar ratio of the density perturbations. As a consequence, we find that the local non-Gaussianity and the tensor-to-scalar ratio are compatible with the recent Planck results.