Axion domain wall baryogenesis

TL;DR

This paper introduces a novel baryogenesis mechanism via axion domain wall annihilation, compatible with high-scale inflation and potentially detectable gravitational waves, expanding the understanding of matter-antimatter asymmetry origins.

Contribution

It proposes a new baryogenesis scenario involving axion domain walls, effective over a wide parameter range, and discusses its observational signatures and compatibility with high-scale inflation.

Findings

Baryon asymmetry can be generated through axion domain wall annihilation.

The model suppresses baryonic isocurvature perturbations.

Gravitational waves from domain wall annihilation could be observed in future experiments.

Abstract

We propose a new scenario of baryogenesis, in which annihilation of axion domain walls generates a sizable baryon asymmetry. Successful baryogenesis is possible for a wide range of the axion mass and decay constant, $m \simeq 10^8 -10^{13}$ GeV and $f \simeq 10^{13} - 10^{16}$ GeV. Baryonic isocurvature perturbations are significantly suppressed in our model, in contrast to various spontaneous baryogenesis scenarios in the slow-roll regime. In particular, the axion domain wall baryogenesis is consistent with high-scale inflation which generates a large tensor-to-scalar ratio within the reach of future CMB B-mode experiments. We also discuss the gravitational waves produced by the domain wall annihilation and its implications for the future gravitational wave experiments.