On the wall velocity dependence of electroweak baryogenesis

TL;DR

This paper revisits supersonic electroweak baryogenesis by incorporating higher-order non-equilibrium fluctuations in the fluid approximation, challenging standard assumptions and supporting the viability of baryogenesis at high wall velocities.

Contribution

It introduces a generalized fluid Ansatz with higher-order terms for transport analysis in electroweak baryogenesis, providing a more comprehensive framework.

Findings

Higher-order fluctuations significantly impact baryogenesis calculations.

Supersonic wall velocities can still facilitate baryogenesis.

Standard treatments may overlook important non-equilibrium effects.

Abstract

We re-evaluate the status of supersonic electroweak baryogenesis using a generalized fluid Ansatz for the non-equilibrium distribution functions. Instead of truncating the expansion to first order in momentum, we allow for higher order terms as well, including up to 21 fluctuations. The collision terms are computed analytically at leading-log accuracy. We also point out inconsistencies in the standard treatments of transport in electroweak baryogenesis, arguing that one cannot do without specifying an Ansatz for the distribution function. We present the first analysis of baryogenesis using the fluid approximation to higher orders. Our results support the recent findings that baryogenesis may indeed be possible even in the presence of supersonic wall velocities.