# Baryogenesis at a Lepton-Number-Breaking Phase Transition

## TL;DR

This paper explores a novel baryogenesis mechanism involving a first-order lepton-number-breaking phase transition, which can produce observable gravitational waves and other cosmological signatures.

## Contribution

It introduces a new scenario where lepton-number breaking during a phase transition generates baryon asymmetry, linking it to gravitational wave signals and dark matter candidates.

## Key findings

- Lepton-number asymmetry can be generated at bubble walls during phase transition.
- The model predicts a stochastic gravitational wave background from bubble collisions.
- Additional signatures include topological defects and a majoron as dark matter.

## Abstract

We study a scenario in which the baryon asymmetry of the universe arises from a cosmological phase transition where lepton-number is spontaneously broken. If the phase transition is first order, a lepton-number asymmetry can arise at the bubble wall, through dynamics similar to electroweak baryogenesis, but involving right-handed neutrinos. In addition to the usual neutrinoless double beta decay in nuclear experiments, the model may be probed through a variety of "baryogenesis by-products," which include a stochastic background of gravitational waves created by the colliding bubbles. Depending on the model, other aspects may include a network of topological defects that produce their own gravitational waves, additional contribution to dark radiation, and a light pseudo-Goldstone boson (majoron) as dark matter candidate.