Sterile Neutrinos and B-L Symmetry

TL;DR

This paper explores how the breaking of B-L symmetry relates to neutrino masses, proposing mechanisms for Dirac and Majorana neutrinos, predicting light sterile neutrinos, and analyzing implications for lepton number violation and cosmology.

Contribution

It introduces simple mechanisms for neutrino mass generation within B-L symmetry models, including predictions of very light sterile neutrinos and detailed analysis of lepton number violating processes.

Findings

Existence of light sterile neutrinos below 1 eV predicted.

Detailed predictions for mu to e and mu to e gamma processes.

Cosmological constraints on relativistic degrees of freedom analyzed.

Abstract

We revisit the relation between the neutrino masses and the spontaneous breaking of the B-L gauge symmetry. We discuss the main scenarios for Dirac and Majorana neutrinos and point out two simple mechanisms for neutrino masses. In this context the neutrino masses can be generated either at tree level or at quantum level and one predicts the existence of very light sterile neutrinos with masses below the eV scale. The predictions for lepton number violating processes such as mu to e and mu to e gamma are discussed in detail. The impact from the cosmological constraints on the effective number of relativistic degree of freedom is investigated.