Strong electroweak phase transition in $t$-channel simplified dark matter models

TL;DR

This paper investigates a dark matter model that can simultaneously explain the observed dark matter density and produce a strong electroweak phase transition, potentially addressing two fundamental cosmological issues.

Contribution

It links perturbative phase transition analysis with dark matter density calculations in a specific inert Majorana fermion model with a scalar mediator.

Findings

Identifies parameter regions with correct dark matter density and strong first-order phase transition.

Shows these regions evade current collider constraints.

Demonstrates the model's potential to explain both dark matter and baryogenesis.

Abstract

Beyond the Standard Model physics is required to explain both dark matter and the baryon asymmetry of the universe, the latter possibly generated during a strong first-order electroweak phase transition. While many proposed models tackle these problems independently, it is interesting to inquire whether the same model can explain both. In this context, we link state-of-the-art perturbative assessments of the phase transition thermodynamics with the extraction of the dark matter energy density. These techniques are applied to a next-to-minimal dark matter model containing an inert Majorana fermion that is coupled to Standard Model leptons via a scalar mediator, where the mediator interacts directly with the Higgs boson. For dark matter masses 180 GeV $ < M_\chi <$ 300 GeV, we discern regions of the model parameter space that reproduce the observed dark matter energy density and allow for a first-order phase transition, while evading the most stringent collider constraints.