Baryogenesis and Dark Matter with Vector-like Fermions

TL;DR

This paper explores how vector-like fermions can simultaneously serve as dark matter candidates and facilitate electroweak baryogenesis, identifying viable parameter regions that satisfy current experimental constraints.

Contribution

It demonstrates that vector-like fermions can unify dark matter and baryogenesis explanations within a single model, considering experimental and theoretical constraints.

Findings

Viable parameter space exists for the model respecting current constraints.

Large Yukawa couplings are needed for a strong first-order phase transition.

The model can potentially explain both dark matter and baryogenesis simultaneously.

Abstract

We show that vector-like fermions can act as the dark matter candidate in the universe whilst also playing a crucial role in electroweak baryogenesis through contributing to the barrier in the one-loop thermal scalar potential. In order for the new fermions to give rise to a strong first order phase transition, we show that one requires rather large Yukawa couplings in the new sector, which are strongly constrained by electroweak precision tests and perturbativity. Strong couplings between the dark matter candidate and the Higgs boson intuitively lead to small values of the relic density and problems with dark matter direct detection bounds. Nevertheless, when considering the most general realisation of the model, we find regions in the parameter space that respect all current constraints and may explain both mysteries simultaneously.