Bilarge Neutrino Mixing and Abelian Flavor Symmetry

TL;DR

This paper investigates two specific bilarge neutrino mixing patterns within Abelian flavor symmetry frameworks, constructing explicit models that align with observed neutrino mixing angles and extending them to quark sectors in grand unified theories.

Contribution

It introduces two novel bilarge neutrino mixing textures, identifies the necessary flavor symmetries for each, and develops explicit models compatible with grand unification.

Findings

Models successfully reproduce neutrino mixing angles.

Flavor symmetries required are U(1)×Z_m and U(1)×Z_m×Z_n.

Framework extends to quark sector with SU(5) GUT.

Abstract

We explore two bilarge neutrino mixing anz$\ddot{a}$tze within the context of Abelian flavor symmetry theories: ($\mathrm{\tt BL_1}$) $\sin\theta_{12}\sim\lambda$, $\sin\theta_{13}\sim\lambda$, $\sin\theta_{23}\sim\lambda$, and ($\mathrm{\tt BL_2}$) $\sin\theta_{12}\sim\lambda$, $\sin\theta_{13}\sim\lambda$, $\sin\theta_{23}\sim 1-\lambda$. The first pattern is proposed by two of us and is favored if the atmospheric mixing angle $\theta_{23}$ lies in the first octant, while the second one is preferred for the second octant of $\theta_{23}$. In order to reproduce the second texture, we find that the flavor symmetry should be $U(1)\times Z_m$, while for the first pattern the flavor symmetry should be extended to $U(1)\times Z_m\times Z_n$ with $m$ and $n$ of different parity. Explicit models for both mixing patterns are constructed based on the flavor symmetries $U(1)\times Z_3\times Z_4$ and $U(1)\times Z_2$. The models are extended to the quark sector within the framework of SU(5) grand unified theory in order to give a successful description of quark and lepton masses and mixing simultaneously. Phenomenological implications are discussed.