A Dynamical Solution to the Axion Domain Wall Problem

TL;DR

This paper proposes a new dynamic mechanism involving multiple scalar fields during and after inflation that resolves the axion domain wall and isocurvature problems, broadening the viable model space.

Contribution

It introduces a novel mechanism that allows axion models with non-trivial domain wall numbers to be compatible with high-scale inflation.

Findings

Compatible with large Hubble parameter inflation

Avoids the isocurvature problem

Increases model-building flexibility

Abstract

The domain wall problem and the isocurvature problem restrict possible combinations of axion models and inflation models. In this paper, we considered a new mechanism which solves those problems by dynamics of multiple scalar fields during/after inflation. The mechanism makes axion models with a non-trivial domain wall number compatible with inflation models with a large Hubble parameter, $H_{I} \gg 10^{7\mbox{-}8}\,$GeV. The mechanism also avoids the isocurvature problem. This mechanism increases the freedom of choice of combinations of axion models and inflation models.