Evolution of String-Wall Networks and Axionic Domain Wall Problem

TL;DR

This paper investigates the evolution and decay of axion-related domain wall networks in the universe, providing constraints on model parameters and exploring gravitational wave detection prospects.

Contribution

It offers the first detailed lattice simulation analysis of metastable domain wall decay in axion models, linking numerical results to cosmological constraints.

Findings

Decay rate estimates for domain walls

Constraints on bias parameter and Peccei-Quinn scale

Potential for gravitational wave detection from domain walls

Abstract

We study the cosmological evolution of domain walls bounded by strings which arise naturally in axion models. If we introduce a bias in the potential, walls become metastable and finally disappear. We perform two dimensional lattice simulations of domain wall networks and estimate the decay rate of domain walls. By using the numerical results, we give a constraint for the bias parameter and the Peccei-Quinn scale. We also discuss the possibility to probe axion models by direct detection of gravitational waves produced by domain walls.