Leptogenesis with testable Dirac neutrino mass generation

Abstract

A TeV-scale Higgs doublet can acquire a tiny vacuum expectation value via its small mixing with the standard model Higgs doublet. This new Higgs doublet then can offer a testable Dirac neutrino mass generation through its sizable Yukawa couplings with several right-handed neutrinos and the standard model lepton doublets. We show the small mixing between the two Higgs doublets can be naturally induced by a seesaw mechanism after an additional symmetry is spontaneously broken. In association with the second Higgs doublet decays, this seesaw mechanism can also accommodate a leptogenesis mechanism to generate the baryon asymmetry in the universe.