Exploring the Neutrino Sector of the Minimal Left-Right Symmetric Model

TL;DR

This paper investigates the neutrino sector of the minimal left-right symmetric model with charge conjugation symmetry, analyzing how it explains neutrino masses and predicts observable lepton flavor violation and electric dipole moments, constrained by current experimental data.

Contribution

It provides a detailed analysis of the parameter space where type-I and type-II seesaw mechanisms are equally responsible for neutrino masses, deriving limits from various experimental constraints.

Findings

Sizable lepton flavor violation is expected unless specific conditions are met.

Stringent limits on heavy neutrino masses and mixing angles are established.

Future experiments could probe remaining viable parameter space.

Abstract

We explore the neutrino sector of the minimal left-right symmetric model, with the additional charge conjugation discrete symmetry, in the tuned regime where type-I and type-II seesaw mechanisms are equally responsible for the light neutrino masses. We show that unless the charged lepton mixing matrix is the identity and the right handed neutrino mass matrix has no phases, we expect sizable lepton flavor violation and electron dipole moment in this region. We use results from recent neutrino oscillation fits, bounds on neutrinoless double beta decay, $\mu \to e \gamma$, $\mu \to 3 e$, $\mu \to e$ conversion in nuclei, the muon anomalous magnetic moment, the electron electric dipole moment and cosmology to determine the viability of this region. We derive stringent limits on the heavy neutrino masses and mixing angles as well as on the vacuum expectation value $v_L$, which drives the type-II seesaw contribution, using the current data. We discuss the perspectives of probing the remaining parameter space by future experiments.