Cosmological Consequences of Domain Walls Biased by Quantum Gravity

TL;DR

This paper investigates how quantum gravity-induced symmetry breaking can lead to the annihilation of domain walls in the early universe, affecting dark matter, gravitational waves, and other cosmological phenomena.

Contribution

It introduces a novel mechanism where quantum gravity effects break discrete symmetries, causing domain wall annihilation and exploring its cosmological consequences.

Findings

Quantum gravity effects can induce domain wall annihilation.

Implications for dark radiation and dark matter are analyzed.

Potential signatures include gravitational waves and primordial black holes.

Abstract

One of the simplest standard model extensions leading to a domain wall network is a real scalar $S$ with a $Z_2$ symmetry spontaneously broken during universe evolution. Motivated by the swampland program, we explore the possibility that quantum gravity effects are responsible for violation of the discrete symmetry, triggering the annihilation of the domain wall network. We explore the resulting cosmological implications in terms of dark radiation, dark matter, gravitational waves, primordial black holes, and wormholes connected to baby universes.