Masses and Mixing of Neutral Leptons in a Grand Unified E_6 Model with Intermediate Pati-Salam Symmetry

TL;DR

This paper reviews E6 grand unified models with intermediate Pati-Salam symmetry, focusing on neutrino masses and mixings, and discusses the implications of hierarchical symmetry breaking chains on neutrino properties.

Contribution

It constructs the neutrino mass and mixing matrix within an E6 model with Pati-Salam symmetry, highlighting the effects of symmetry breaking patterns.

Findings

Neutrino mass and mixing matrices are explicitly derived.

Constraints on neutrino mixing parameters are discussed.

Hierarchical symmetry breaking influences neutrino properties.

Abstract

A brief review of the assignment of elementary fermions and bosons to irreducible multiplets in grand unified $E_6$ models is followed by a discussion of different, hierarchical symmetry breaking chains from $E_6$ down to $SU(3)_C \times U(1)_{EM}$. We concentrate here on a model with an intermediate Pati-Salam symmetry for which $(B-L)$ is conserved. In particular, the mass/mixing matrix of electrically neutral fermions (i.e.neutrinos) that would be derived from Yukawa couplings is constructed. The pattern of neutrino masses and some bounds on mixing parameters are discussed.