Seesaw Neutrino Mass and New U(1) Gauge Symmetry

TL;DR

This paper explores how small neutrino masses can be generated via seesaw mechanisms involving Majorana fermions and investigates new U(1) gauge symmetries arising from these models, with implications for particle physics phenomenology.

Contribution

It introduces two variations of a new U(1)_X gauge symmetry compatible with seesaw neutrino mass models involving Majorana fermions.

Findings

Two models with different fermion configurations are proposed.

Phenomenological consequences of the models are discussed.

The models extend gauge symmetry understanding in neutrino physics.

Abstract

The three electroweak doublet neutrinos $\nu_{e,\mu,\tau}$ of the Standard Model may acquire small seesaw masses, using either three Majorana fermion singlets $N$ or three Majorana fermion triplets $(\Sigma^+,\Sigma^0,\Sigma^-)$. It is well-known that the former accommodates the U(1) gauge symmetry $B-L$. It has also been shown some years ago that the latter supports a new $U(1)_X$ gauge symmetry. Here we study two variations of this $U(1)_X$, one for two $N$ and one $\Sigma$, the other for one $N$ and two $\Sigma$. Phenomenological consequences are discussed.