Neutrino models with a zero mass eigenvalue

TL;DR

This paper explores neutrino models with a zero mass eigenvalue, analyzing their compatibility with oscillation data and baryon asymmetry, under specific assumptions about right-handed neutrino mass origins.

Contribution

It proposes and examines neutrino models with a zero mass eigenvalue, considering their implications for neutrino oscillations and baryon asymmetry within a seesaw framework.

Findings

Models with a zero mass eigenvalue are consistent with current oscillation data.

Certain assumptions about right-handed neutrino mass origins support these models.

Implications for neutrino mass hierarchy and cosmological observations.

Abstract

Absolute values of the neutrino mass are not known still now although their upper bounds are constrained through several experiments and observations. Recent analyses of cosmological observations present severe constraint on the sum of neutrino masses. It might suggest an interesting possibility for the absolute values of neutrino mass and their ordering. In this paper, taking it as a useful hint, we study possible neutrino models with a zero mass eigenvalue from a view point of neutrino oscillation data and baryon number asymmetry in the Universe. We focus our study on the seesaw type mass generation by making a certain assumption for origin of right-handed neutrino mass.