Baryogenesis in the Zee-Babu model with arbitrary $\xi$ gauge

TL;DR

This paper investigates the electroweak phase transition in the Zee-Babu model, finding it to be a strong first-order transition at 100 GeV influenced by new bosons and gauge choices, with implications for baryogenesis.

Contribution

It demonstrates that the Zee-Babu model supports a strong first-order electroweak phase transition, unaffected by gauge choice, and identifies the role of new bosons in strengthening the transition.

Findings

EWPT is first-order at 100 GeV with strength 1 to 4.15.

Charged Higgs bosons are lighter than 300 GeV.

Gauge choice does not affect the first-order nature of EWPT.

Abstract

We consider the baryogenesis picture in the Zee-Babu model. Our analysis shows that electroweak phase transition (EWPT) in the model is a first-order phase transition at the $100$ GeV scale, its strength ranges from 1 to 4.15 and the masses of charged Higgs boson are smaller than $300$ GeV. The EWPT is strengthened by only the new bosons and this strength is enhanced by arbitrary $\xi$ gauge. However, the $\xi$ gauge does not break the first-order EWPT or, in other words, the $\xi$ gauge is not the cause of the EWPT. This leads to the fact that the calculation of EWPT in Landau gauge is enough; and the latter may provide baryon-number violation (B-violation) necessary for baryogenesis in the relationship with nonequilibrium physics in the early universe.