Early Universe hypercharge breaking and neutrino mass generation

TL;DR

This paper explores how early Universe hypercharge symmetry breaking in models with radiative neutrino mass generation can enable novel baryogenesis mechanisms, linking neutrino physics with matter-antimatter asymmetry.

Contribution

It demonstrates that hypercharge breaking before electroweak symmetry breaking can facilitate baryogenesis in models like Zee-Babu, offering new insights into early Universe physics.

Findings

Hypercharge breaking can occur in radiative neutrino mass models.

Such breaking enables non-conventional leptogenesis mechanisms.

Potential explanation for matter-antimatter asymmetry.

Abstract

We show that the conditions allowing for a spontaneous breaking of the $U(1)_Y$ hypercharge gauge symmetry of the Standard Model (SM) in the early Universe are generically present in extensions of the SM addressing the generation of light neutrino masses via radiative contributions. In such scenarios, the breaking of (hyper)charge at high-temperatures yields new possibilities for explaining the observed matter-antimatter asymmetry of the Universe. Considering for concreteness the Zee-Babu radiative neutrino mass generation model, we show that a period of hypercharge breaking prior to the electroweak phase transition could allow for successful baryogenesis via a non-conventional leptogenesis mechanism, based on the presence of charge-breaking masses for the SM leptons in the early Universe.