Electroweak sphalerons in the reduced minimal 3-3-1 model

TL;DR

This paper calculates electroweak sphaleron rates in the reduced minimal 3-3-1 model, showing their behavior across two phase transitions in the early Universe, which could facilitate baryogenesis.

Contribution

It provides the first detailed analysis of sphaleron rates in the RM331 model during early Universe phase transitions.

Findings

Sphaleron rates exceed the expansion rate before phase transitions.

Sphaleron processes decouple after phase transitions.

Potential implications for baryogenesis in the early Universe.

Abstract

We calculate the electroweak sphaleron rates in the reduced minimal 3-3-1 (RM331) model. In the context of the early Universe, this model undergoes a sequence of two first-order phase transitions, $SU(3) \rightarrow SU(2)$ at the TeV scale and $SU(2)\rightarrow U(1)$ at the $10^2$ GeV scale, as the Universe cools down from the hot big bang. By a thin-wall approximation, we show that for each phase transition in this sequence, the sphaleron rate is larger than the cosmological expansion rate at temperatures higher than the critical temperature, and after the phase transition, the sphaleron process is decoupled. This may provide baryon-number violation (B violation) necessary for baryogenesis in the relationship with nonequilibrium physics in the early Universe.