Electroweak baryogenesis between broken phases in multi-step phase transition

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.