Electroweak Symmetry Restoration in the N2HDM via Domain Walls

TL;DR

This paper explores how domain walls in the N2HDM can restore electroweak symmetry locally, potentially impacting early universe cosmology and enabling electroweak baryogenesis.

Contribution

It demonstrates the possibility of electroweak symmetry restoration within domain walls in the N2HDM, a novel mechanism relevant for early universe cosmology.

Findings

Electroweak symmetry can be restored inside domain walls.

Domain walls may host CP-violating vacua.

Implications for electroweak baryogenesis are discussed.

Abstract

Domain walls are a type of topological defects that can arise in the early universe after the spontaneous breaking of a discrete symmetry. They can form in several beyond the Standard Model theories with an extended Higgs sector such as the Next to-Two-Higgs-Doublet model (N2HDM). In this work, we discuss the domain wall solution related to the singlet scalar of the N2HDM and demonstrate the possibility of restoring the electroweak symmetry inside and in the vicinity of the domain wall. Such symmetry restoration can have profound implications on early universe cosmology as the weak sphaleron rate inside the domain wall would, in principle, be unsuppressed compared to the rate outside the wall. We also discuss the possibility of generating CP-violating vacua localized in the vicinity of the domain wall. Our work is a first step towards the realization of electroweak baryogenesis mediated by domain walls in the N2HDM.