Generalized Friedberg-Lee model for neutrino masses and leptonic CP violation from mu-tau symmetry breaking

TL;DR

This paper extends the Friedberg-Lee neutrino mass model to include CP violation, demonstrating how mu-tau symmetry breaking can produce realistic neutrino mixing patterns and CP phases.

Contribution

It introduces a generalized Friedberg-Lee model with complex parameters to incorporate CP violation and mu-tau symmetry breaking in neutrino masses.

Findings

A neutrino mixing pattern with heta_12 ≈ 35.3°, heta_23=45°, heta_13 ≠ 0°, ext{and} \, ext{δ}=90° can be derived.

A method to obtain nearly tri-bimaximal mixing with δ=0° and Majorana phases is proposed.

The model naturally explains observed neutrino mixing angles and CP violation phases.

Abstract

Assuming the Majorana nature of massive neutrinos, we generalize the Friedberg-Lee neutrino mass model to include CP violation in the neutrino mass matrix M_\nu. The most general case with all the free parameters of M_\nu being complex is discussed. We show that a favorable neutrino mixing pattern (with \theta_12 \approx 35.3^\circ, \theta_23=45^\circ, \theta_13 \neq 0^\circ and \delta=90^\circ) can naturally be derived from M_\nu, if it has an approximate or softly-broken \mu-\tau symmetry. We also point out a different way to obtain the nearly tri-bimaximal neutrino mixing pattern with \delta=0^\circ and non-vanishing Majorana phases.