Bubble wall velocities in the Standard Model and beyond

TL;DR

This paper calculates bubble wall velocities and thicknesses during a cosmological first-order phase transition in the Standard Model and its minimal extensions, focusing on electroweak symmetry breaking and plasma properties.

Contribution

It provides a simplified framework to determine bubble wall dynamics based on plasma properties, applicable to a broad class of models beyond the Standard Model.

Findings

Bubble wall velocity depends on phase transition strength and pressure difference.

Wall thickness can be deduced from plasma equilibrium properties.

Results are applicable to minimal Standard Model extensions.

Abstract

We present results for the bubble wall velocity and bubble wall thickness during a cosmological first-order phase transition in a condensed form. Our results are for minimal extensions of the Standard Model but in principle are applicable to a much broader class of settings. Our first assumption about the model is that only the electroweak Higgs is obtaining a vacuum expectation value during the phase transition. The second is that most of the friction is produced by electroweak gauge bosons and top quarks. Under these assumptions the bubble wall velocity and thickness can be deduced as a function of two equilibrium properties of the plasma: the strength of the phase transition and the pressure difference along the bubble wall.