Connecting Leptonic CP Violation, Lightest Neutrino Mass and Baryon Asymmetry Through Type II Seesaw

TL;DR

This paper explores how a combined type I and type II seesaw model can link leptonic CP violation, neutrino mass, and baryon asymmetry, providing a comprehensive framework for understanding neutrino physics and matter-antimatter imbalance.

Contribution

It introduces a general form of type II seesaw mass matrix that explains neutrino mixing angles, CP violation, and baryon asymmetry within a unified model.

Findings

Correlates type II seesaw term with CP phase and neutrino mass

Constrains CP phase using baryon asymmetry data

Demonstrates compatibility with observed neutrino mixing angles

Abstract

We study the possibility of connecting leptonic Dirac CP phase $\delta$, lightest neutrino mass and baryon asymmetry of the Universe within the framework of a model where both type I and type II seesaw mechanisms contribute to neutrino mass. Type I seesaw gives rise to Tri-Bimaximal (TBM) type neutrino mixing whereas type II seesaw acts as a correction in order to generate non-zero $\theta_{13}$. We derive the most general form of type II seesaw mass matrix which can not only give rise to correct neutrino mixing angles but also can generate non-trivial value of $\delta$. Considering both the cases where type II seesaw is sub-leading and is equally dominant compared to type I seesaw, we correlate the type II seesaw term with $\delta$ and lightest neutrino mass. We further constrain the Dirac CP phase $\delta$ and hence the type II seesaw mass matrix from the requirement of producing the observed baryon asymmetry through the mechanism of leptogenesis.