# Baryon asymmetry from left-right phase transition

## TL;DR

This paper proposes a left-right symmetric model with mirror fermions where a first-order phase transition generates baryon asymmetry via CP-violating mirror fermion reflections, linking it to neutrino CP phases and TeV-scale new particles.

## Contribution

It introduces a novel mechanism for baryogenesis involving mirror fermions and a first-order phase transition, connecting CP violation in neutrinos to cosmic baryon asymmetry.

## Key findings

- Mirror fermion reflections produce lepton and baryon asymmetries during phase transition.
- The model explains baryon asymmetry using neutrino CP phases and parity symmetry.
- TeV-scale mirror fermions and Higgs triplet are compatible with current collider constraints.

## Abstract

We extend the standard model fermions by a mirror copy to realize a left-right symmetry. During a strongly first order phase transition of the spontaneous left-right symmetry breaking, the CP-violating reflections of the mirror fermions off the mirror Higgs bubbles can generate a mirror lepton asymmetry and an equal mirror baryon asymmetry. We then can obtain an ordinary baryon asymmetry through the mirror fermion decays where a dark matter scalar plays an essential role. Benefitted from a parity symmetry for solving the strong CP problem, the cosmic baryon asymmetry can be well described by the ordinary lepton mass matrices up to an overall factor. In this scenario, the Dirac CP phase in the Majorana neutrino mass matrix can provide a unique source for the required CP violation. Furthermore, the Higgs triplet for type-II seesaw as well as the first generation of mirror charged fermions can be allowed at the TeV scale.