Strongly First Order Phase Transitions Near an Enhanced Discrete Symmetry Point

TL;DR

This paper introduces a group theoretic criterion to identify parameter regions in extended Standard Model frameworks where the electroweak phase transition is strongly first order, facilitating electroweak baryogenesis and related cosmological phenomena.

Contribution

It presents a novel symmetry-based approach to locate strong first order phase transitions near enhanced discrete symmetry points in model parameter space.

Findings

Identification of parameter regions with strong first order phase transitions

Implications for dark matter and gravitational wave signals

Application to specific electroweak symmetry breaking models

Abstract

We propose a group theoretic condition which may be applied to extensions of the Standard Model in order to locate regions of parameter space in which the electroweak phase transition is strongly first order, such that electroweak baryogenesis may be a viable mechanism for generating the baryon asymmetry of the universe. Specifically, we demonstrate that the viable corners of parameter space may be identified by their proximity to an enhanced discrete symmetry point. At this point, the global symmetry group of the theory is extended by a discrete group under which the scalar sector is non-trivially charged, and the discrete symmetry is spontaneously broken such that the discrete symmetry relates degenerate electroweak preserving and breaking vacua. This idea is used to investigate several specific models of the electroweak symmetry breaking sector. The phase transitions identified through this method suggest implications for other relics such as dark matter and gravitational waves.