Electroweak baryogenesis from a dark sector

Understand

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.