Description
In this talk we will explore how extensions of the Standard Model (SM) scalar sector featured in radiative neutrino mass models can generically accommodate U(1)_Y gauge symmetry breaking in the early Universe. Using the Zee-Babu neutrino mass generation model as a template, we investigate the rich phenomenology that arises when accounting for such high-temperature hypercharge symmetry non-restoration in addition to electroweak (EW) symmetry breaking of the standard thermal history. Our focus lies on the baryon asymmetry generating mechanisms which emerge according to subtleties in these thermal histories. Generally, we find that such settings give rise to phase structures which permit strong first order EW phase transitions as needed for EW baryogenesis whilst comfortably allowing for evasion of present experimental constraints on the lepton and scalar sectors. Furthermore, we discuss a novel leptogenesis mechanism which crucially relies on the high-temperature U(1)_Y breaking phase and the exotic phenomenology of charge-breaking SM lepton masses therein.
