Leptogenesis from left-handed neutrino production during axion inflation

TL;DR

This paper presents a mechanism where axion-driven inflation coupled with neutrinos naturally produces the matter-antimatter asymmetry observed in the universe through leptogenesis.

Contribution

It introduces a novel scenario linking axion inflation, neutrino helicity asymmetry, and baryogenesis, with specific assumptions about neutrino masses and Higgs dynamics during inflation.

Findings

Helicity asymmetry in neutrinos is generated during axion inflation.

The neutrino helicity asymmetry is converted into a net lepton number after inflation.

The lepton asymmetry is partially converted into baryon asymmetry via sphalerons.

Abstract

We propose that the observed matter-antimatter asymmetry can be naturally produced as a byproduct of axion-driven slow-roll inflation by coupling the axion to standard-model neutrinos. We assume that GUT scale right-handed neutrinos are responsible for the masses of the standard model neutrinos and that the Higgs field is light during inflation and develops a Hubble scale vacuum expectation value (VEV). In this set up, the rolling axion generates a helicity asymmetry in standard-model neutrinos. Following inflation, this helicity asymmetry becomes equal to a net lepton number as the Higgs VEV decays and is partially re-processed by the $SU(2)_{L}$ sphaleron into a net baryon number.