Analysis of four-zero textures in the 3 + 1 neutrino framework.

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--A in which the value of mass matrix element Mee is zero and class B in which Mee is nonzero. 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 Mαβ, 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. [ABSTRACT FROM AUTHOR]