Leptogenesis from low-energy CP violation in minimal left-right symmetric model

TL;DR

This paper demonstrates that in minimal left-right symmetric models, low-energy CP violation can generate the observed baryon asymmetry through leptogenesis, linking low-energy neutrino measurements with early universe baryogenesis.

Contribution

It shows that low-energy CP phases in minimal left-right models can account for leptogenesis, connecting neutrino physics with baryon asymmetry generation.

Findings

Low-energy CP phases can produce the observed baryon asymmetry.

Dirac CP phase can be the sole source of CP violation for leptogenesis.

Models are testable via next-generation neutrinoless double-beta decay experiments.

Abstract

We perform a thermal unflavored leptogenesis analysis on minimal left-right symmetric models with discrete left-right symmetry identified as generalized parity or charge conjugation. When left-right symmetry is unbroken in the lepton Yukawa sector, the neutrino Dirac coupling matrix is completely determined by neutrino masses and mixing angles, allowing CP violation needed to generate leptogenesis totally resides in the low-energy sector. With two lepton asymmetry generation ways, both type I and mixed type I$+$II neutrino mass generation mechanisms are considered. After solving the Boltzmann equations numerically, we find that the low-energy CP phases in the lepton mixing matrix can successfully produce the observed baryon asymmetry, and in some cases, the Dirac CP phase can be the only source of CP violation. Finally, we discuss the interplay among low-energy CP phase measurements, leptogenesis, and neutrinoless double beta decay. We show that the viable models for successful leptogenesis can be probed in next-generation neutrinoless double-beta decay experiments.