B-L Neutrinos

TL;DR

This paper analyzes neutrino masses and mixings within a B-L symmetric model, suggesting neutrinos are nearly Dirac particles with suppressed neutrinoless double-beta decay, and explains tiny mass differences naturally.

Contribution

It introduces a B-L symmetric framework with a 6x6 mass matrix that naturally accounts for tiny neutrino mass differences and predicts suppressed neutrinoless double-beta decay.

Findings

Neutrinos are nearly Dirac fermions.

Neutrino oscillations mainly between flavor and sterile states.

Neutrinoless double-beta decay is highly suppressed.

Abstract

Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu=0 for Dirac neutrinos and theta_nu=pi/2 for Majorana neutrinos. At theta_nu = 0 baryon-minus-lepton number is conserved. If theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the tiny mass differences exhibited in the solar and atmospheric neutrino experiments are naturally explained by the approximate conservation of B-L. Neutrinos are nearly Dirac fermions. This B-L model leads to these predictions: neutrinos oscillate mainly between flavor eigenfields and sterile eigenfields, and so the appearance of neutrinos and antineutrinos is suppressed; neutrinos may well be of cosmological importance; in principle the disappearance of the tau neutrino should be observable; and neutrinoless double-beta decay is suppressed by an extra factor of 10^(-5) and so will not be seen in the Heidelberg/Moscow, IGEX, GENIUS, or CUORE experiments.