Phenomenological study of extended seesaw model for light sterile neutrino

Abstract

We study the zero textures of the Yukawa matrices in the Minimal Extended type-I Seesaw (MES) model which can give rise to ∼ eV scale sterile neutrinos. In this model, three right handed neutrinos and one extra singlet S are added to generate a light sterile neutrino. The light neutrino mass matrix for the active neutrinos, m_ν, depends on the Dirac neutrino mass matrix (M_D), Majorana neutrino mass matrix (M_R) and the mass matrix (M_S) coupling the right handed neutrinos and the singlet. The model predicts one of the light neutrino masses to vanish. We systematically investigate the zero textures in M_D and observe that maximum five zeros in M_D can lead to viable zero textures in m_ν. For this study we consider four different forms for M_R (one diagonal and three off diagonal) and two different forms of (M_S) containing one zero. Remarkably we obtain only two allowed forms of m_ν (m_eτ = 0 and m_ττ = 0) having inverted hierarchical mass spectrum. We re-analyze the phenomenological implications of these two allowed textures of m_ν in the light of recent neutrino oscillation data. In the context of the MES model, we also express the low energy mass matrix, the mass of the sterile neutrino and the active-sterile mixing in terms of the parameters of the allowed Yukawa matrices. The MES model leads to some extra correlations which disallow some of the Yukawa textures obtained earlier, even though they give allowed one-zero forms of m_ν. We show that the allowed textures in our study can be realized in a simple way in a model based on MES mechanism with a discrete Abelian flavor symmetry group Z₈ × Z₂.