Leptogenesis in Inflationary models with Non-Abelian Gauge Fields

TL;DR

This paper proposes a natural leptogenesis mechanism during inflation driven by non-Abelian gauge fields, leveraging parity-violating tensor modes to generate the observed baryon asymmetry.

Contribution

It introduces a novel leptogenesis scenario in non-Abelian gauge field inflation models, linking parity violation in tensor modes to baryon asymmetry generation.

Findings

Parity-violating tensor modes are present in non-Abelian gauge field inflation models.

The gravitational chiral anomaly can produce lepton asymmetry during inflation.

Parameter ranges can explain the observed baryon-to-photon ratio.

Abstract

A scenario of leptogenesis was introduced in [1] which works during inflationary period within standard model of particle physics setup. In this scenario lepton number is created by the gravitational chiral anomaly which has a non-zero expectation value for models of inflation driven by pseudoscalar field(s). Here, we observe that models of inflation involving non-Abelian gauge fields, e.g. the chromo-natural inflation [2] or the gauge-flation [3], have a parity-violating tensor mode (graviton) spectrum and naturally lead to a non-vanishing expectation value for the gravitational chiral anomaly. Therefore, one has a natural leptogenesis scenario associated with these inflationary setups, \emph{inflato-natural leptogenesis}. We argue that the observed value of baryon-to-photon number density can be explained in a natural range of parameters in these models.