Good things to do with extra Higgs doublets

TL;DR

This paper explores models with extra Higgs doublets that can explain matter-antimatter asymmetry and neutrino masses, with potential testability at future colliders and implications for flavor physics.

Contribution

It introduces new multi-Higgs models addressing baryogenesis and neutrino mass generation, incorporating flavor constraints and collider prospects.

Findings

Higgs doublets can generate lepton and baryon asymmetry via CP violation.

Models predict new scalars accessible at future 100 TeV colliders.

Collider data can inform neutrino mass hierarchy.

Abstract

In this contribution to the Snowmass 2021 process, we outline models with two or three Higgs doublets that address open questions of particle physics and cosmology. In particular, we show that with two additional Higgs doublets one can provide a mechanism for the generation of lepton asymmetry and hence baryon asymmetry, through CP violating Higgs decays, near weak scale temperatures. In another model with only one extra Higgs doublet, we illustrate that Yukawa couplings to quarks and neutrinos can lead to a viable mechanism for the generation of Dirac neutrino masses, sourced by the QCD chiral condensate of strange quarks. We adapt Spontaneous Flavor Violation -- a framework for coupling light fermions to new Higgs doublets while avoiding tree level flavor-changing neutral currents -- in constructing these models. In both cases, flavor data provide interesting constraints on the parameter space. Either scenario includes $\mathcal{O}{(1)}$ couplings of light quarks to the Higgs doublets which allow a future 100 TeV $pp$ collider to have reach for the new scalars up to $\mathcal{O}{(10~{\rm TeV})}$ masses, through resonant single production. In the neutrino mass model, collider data can shed light on the mass hierarchy of neutrinos. This article is based on work presented in Refs. [1,2].