Analysis of four-zero textures in $3+1$ framework

TL;DR

This paper investigates four-zero textures in the neutrino mass matrix within a 3+1 framework, identifying allowed textures and their implications for neutrino hierarchy and neutrinoless double beta decay.

Contribution

First analysis of four-zero neutrino mass matrix textures in 3+1 scheme, classifying allowed textures and exploring their phenomenological implications.

Findings

Only 15 out of 210 textures are allowed.

Different textures are permitted for normal and inverted hierarchies.

Implications for neutrinoless double beta decay experiments.

Abstract

The presence of a zero texture in the neutrino mass matrix can indicate the presence of an underlying symmetry which can generate neutrino mass and mixing. In this paper, for the first time we study the four-zero textures of the low energy neutrino mass matrix in the presence of an extra light-sterile neutrino i.e., the 3+1 neutrino scheme. In our analysis we find that out of the 210 possible four-zero textures only 15 textures are allowed. We divide the allowed four-zero textures into two classes -- class $A$ in which the value of mass matrix element $M_{ee}$ is zero and class $B$ in which $M_{ee}$ is non-zero. In this way we obtain ten possible four-zero textures in class $A$ and five possible four-zero textures in class $B$. In our analysis we find that, for normal hierarchy the allowed number of textures in class $A$ ($B$) is nine (three). For the case of inverted hierarchy we find that, two textures in class $A$ are disallowed and these textures are different from the disallowed textures for normal hierarchy in class $A$. However, we find that all the five textures in class $B$ are allowed for the inverted hierarchy. Based on analytic expressions for the elements $M_{\alpha\beta}$, we discuss the reasons for certain textures being disallowed. We also discuss the correlations between the different parameters of the allowed textures. Finally, we present the implications of our study on experimental searches for neutrinoless double beta decay.