Non-Gaussianity from Axion-Gauge Fields Interactions during Inflation

TL;DR

This paper investigates how axion and SU(2) gauge field interactions during inflation produce non-Gaussian signals and chiral gravitational waves, significantly enhancing the three-point function compared to standard models.

Contribution

It introduces a model where gauge fields source metric fluctuations at linear order, leading to amplified non-Gaussianity and chiral gravitational waves during inflation.

Findings

Enhanced chiral gravitational wave spectrum.

Larger three-point function amplitude than standard inflation.

Gauge fields source metric fluctuations at linear level.

Abstract

We study the scalar-tensor-tensor non-Gaussian signal in an inflationary model comprising also an axion coupled with SU(2) gauge fields. In this set-up, metric fluctuations are sourced by the gauge fields already at the linear level providing an enhanced chiral gravitational waves spectrum. The same mechanism is at work in generating an amplitude for the three-point function that is parametrically larger than in standard single-field inflation.