Study of Some Possible Textures of Neutrino Mass Matrix

Abstract

Neutrinos are elementary particles that have spin 1

integer, so they are called fermions. They

have small masses compared to the other leptons (e, µ, τ ). Even though neutrinos are one of the most abundant particles in the universe, they are incredibly difficult to detect. They have neither an electric charge nor a color charge. Thus, they interact with matter only via weak and gravitational interactions. Neutrinos are created by different sources such as in beta decay of the nucleus, in nuclear reactions that occur in the core of the stars, in nuclear reactions inside the core of the reactors, during the explosion of the stars, etc. The first one who postulated the existence of neutrinos was Pauli in 1930 to preserve energy, momentum, and angular momentum conservation in beta decay. In 1956, neutrinos were first detected by Frederick Renines, F.B.Harrison, H.W.Kruse, and A.D.McGuire [1]. There are three different types of neutrinos which are called flavors νe, νµ and ντ produced along with e, µ and τ in the weak interactions. For many years physicists considered a neutrino to be a massless particle, but after neutrino oscillations observations [2, 3, 4, 5, 6], we have to consider neutrinos as massive particles, and their mass eigenstates are not degenerate. The interactions between neutrinos and other elementary particles are described within the standard model of the elementary particle physics, which is SU (3)c ⊗ SU (2)L ⊗ U (1)Y gauge theory. However, the matter content of the standard model does not contain right-handed neutrinos. Therefore, the neutrinos are massless particles in that model, but this assumption contradicts the neutrino oscillation observations. To overcome this problem, we have to go beyond the standard model to explain naturally how neutrinos acquire small masses compared to the other leptons. Therefore, the neutrino oscillations were the first firm sign of physics beyond the standard model.