Baryogenesis and EDMs in the 2HDM+CS

TL;DR

This paper explores a novel model combining two Higgs doublets, a scalar, and a Majorana fermion to explain baryogenesis and EDMs, showing that low-scale baryogenesis is feasible and can be linked to observable EDM signals.

Contribution

It introduces a new three-step baryogenesis mechanism in a 2HDM+CS model and analyzes its potential to produce observable EDMs at relatively low energies.

Findings

Baryogenesis can occur with singlet masses as low as 10^5 GeV due to resonant enhancement.

The model can generate large electron and neutron EDMs while explaining baryogenesis.

Baryogenesis and EDM signals can be connected without requiring a first order electroweak phase transition.

Abstract

We perform the first joint analysis of baryogenesis from initial Higgs charges (also called Higgsogenesis) and EDMs in a model with two Higgs doublets, a complex scalar and a Majorana fermion. In our proposed scenario, baryogenesis happens in three steps: (1) The decay of the scalar produces an asymmetry between the two Higgs doublets which is partly transferred to fermions via Standard Model processes. (2) This asymmetry is converted into a $B-L$ charge via interactions mediated by the Majorana fermion. (3) The weak sphaleron processes partially convert the resulting $B-L$ charge into a $B$ asymmetry. We perform a numerical analysis of baryogenesis and the EDM contributions and find that, due to resonant enhancement, baryogenesis is possible with singlet masses as low as $10^5$ GeV. We also find that for some parameters, the model can give large contributions to the electron and neutron EDM while also producing baryogenesis. The present scenario offers a new perspective on interpreting observational bounds in terms of cosmology: Because it relies on out-of-equilibrium decays, the questions of baryogenesis and $CP$ violation in the Higgs sector may be linked with EDM signals without the additional assumption of a first order electroweak phase transition.