Electroweak baryogenesis between broken phases in multi-step phase transition

TL;DR

This paper explores the potential for electroweak baryogenesis during multi-step phase transitions, focusing on the second step where sphaleron suppression can generate sufficient baryon asymmetry, applicable to models with extra scalar fields.

Contribution

It introduces a novel scenario for electroweak baryogenesis occurring between broken phases in multi-step phase transitions, with detailed analysis using a prototypical $SU(2)$ model.

Findings

Second step phase transitions can produce sufficient baryon asymmetry.

Sphaleron rates can be un-suppressed before the second phase transition.

The framework can be applied to models with additional $SU(2)$ scalar fields.

Abstract

Possibility of electroweak baryogenesis (EWBG) via multi-step phase transition (PT) is considered. We investigate the EWBG between $SU(2)$ broken phases in the second step PT of the two-step PT. The produced baryon number asymmetry is evaluated using a prototypical model with a $SU(2)$ charged CP-odd scalar field. We show that the second step PTs where the sphaleron rate is possible to be un-suppressed before the PTs, which can reproduce the sufficient baryon number asymmetry. Our studies can be adapted to models with extra $SU(2)$ scalar fields. We discuss specific models suitable for our scenario.