Baryogenesis via relativistic bubble walls

TL;DR

This paper introduces a new baryogenesis mechanism involving ultra-relativistic bubble walls during a phase transition, which produce heavy particles out-of-equilibrium and induce CP violation, leading to matter-antimatter asymmetry.

Contribution

It demonstrates that relativistic bubble walls can generate CP violation at one-loop level, enabling baryogenesis through heavy particle production during phase transitions.

Findings

Heavy particle production occurs at ultra-relativistic bubble walls.

CP violation is induced at one-loop level during production.

Stochastic gravitational waves are generic signatures of these models.

Abstract

We present a novel mechanism which leads to the baryon asymmetry generation during the strong first order phase transition. If the bubble wall propagates with ultra-relativistic velocities, it has been shown that it can produce states much heavier than the scale of the transition and that those states are then out-of-equilibrium. In this paper, we show that the production mechanism can also induce CP-violation at one-loop level. We calculate those CP violating effects during the heavy particle production and show, that combined with baryon number violating interactions, those can lead to successful baryogenesis. Two models based on this mechanism are constructed and their phenomenology is discussed. Stochastic gravitational wave signals turn out to be generic signatures of this type of models.