# Electroweak baryogenesis from a dark sector

## TL;DR

This paper proposes a UV-complete model where a dark sector with a singlet scalar and fermionic dark matter enables electroweak baryogenesis through CP asymmetry transfer, with potential LHC signatures.

## Contribution

It introduces a novel dark sector model coupling to the Higgs and leptons, demonstrating successful baryogenesis and dark matter relic density within a unified framework.

## Key findings

- The model achieves successful electroweak baryogenesis.
- It predicts detectable signals at the LHC.
- The dark matter relic density matches observations.

## Abstract

Adding an extra singlet scalar $S$ to the Higgs sector can provide a barrier at tree level between a false vacuum with restored electroweak symmetry and the true one. This has been demonstrated to readily give a strong phase transition as required for electroweak baryogenesis. We show that with the addition of a fermionic dark matter particle $\chi$ coupling to $S$, a simple UV-complete model can realize successful electroweak baryogenesis. The dark matter gets a CP asymmetry that is transferred to the standard model through a $CP\ portal\ interaction$, which we take to be a coupling of $\chi$ to $\tau$ leptons and an inert Higgs doublet. The CP asymmetry induced in left-handed $\tau$ leptons biases sphalerons to produce the baryon asymmetry. The model has promising discovery potential at the LHC, while robustly providing a large enough baryon asymmetry and correct dark matter relic density with reasonable values of the couplings.