The LFV charged lepton decays µ → e+γ, τ → e+γ and τ → µ+γ and thermal leptogenesis are analysed in the MSSM with seesaw mechanism of neutrino mass generation and soft SUSY breaking with universal boundary conditions. The case of hierarchical heavy Majorana neutrino mass spectrum, M 1 ≪ M 2 ≪ M 3 , is investigated. Leptogenesis requires M 1 > ∼ 10 9 GeV. Considering the natural range of values ...

Solar and atmospheric neutrino oscillations have established solid evidence for non-vanishing neutrino masses and determined mass squared differences δm and the mixing matrix U with increasing accuracy. The puzzle of the absolute mass scale for neutrinos, though, is still unsolved . In fact it is a true experimental challenge to determine an absolute neutrino mass below 1 eV. Three approaches h...

We discuss the connection between the origin of neutrino masses and their mixings which arises in a class of scenarios with radiatively induced neutrino masses. In these scenarios, the neutrino mass matrix acquires textures with two entries close to zero in the basis where the charged-lepton mass matrix is diagonal. This results in specific constraints on the neutrino mixing parameters, which l...

Recent neutrino experiments suggest the strong evidences of tiny neutrino masses and the lepton-flavor mixing. Neutrino-oscillation solutions for the atmospheric neutrino anomaly and the solar neutrino deficit can determine the texture of neutrino mass matrix according to the neutrino mass hierarchies as Type A: m3 ≫ m2 ∼ m1, Type B: m3 ≪ m2 ∼ m1, and Type C: m3 ∼ m2 ∼ m1. In this paper we stud...

We consider a Mass Varying Neutrinos (MaVaNs) model in supersymmetric theory. The model includes effects of supersymmetry breaking transmitted by the gravitational interaction from the hidden sector, in which supersymmetry was broken, to the dark energy sector. Then evolutions of the neutrino mass and the equation of state parameter of the dark energy are presented in the model. It is remarked ...

I review the subject of double beta decay with emphasis upon its implications for the neutrino. It is shown that even if right-handed currents provide the phenomenological mechanism for no-neutrino decay, the fundamental mechanism underlying the process must be neutrino mass. Estimates of the mass required suggest that this mechanism is less likely than the direct mechanism of Majorana mass ter...

Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved...

Abstract It is found that the seesaw mechanism not only explains the smallness of neutrino masses but also accounts for the large mixing angles simultaneously, even if the unification of the neutrino Dirac mass matrix with that of up-type quark sector is realized. In this mechanism, we show that the mixing matrix of the Dirac-type mass matrix gets extra rotations from the diagonalization of Maj...

The combined requirements, of (i) a natural solution to the fermion mass hierarchy problem and (ii) an explanation of both the atmospheric and solar neutrino problems, lead to an essentially unique picture of neutrino masses and mixing angles. The electron and muon neutrinos are quasi-degenerate in mass with maximal mixing, giving ν e − ν µ vacuum oscillations. The overall neutrino mass scale i...

A model is considered in which the scale of the heavy singlet neutrinos is a few orders of magnitude below the grand unification scale and where righthanded vector bosons play still a negligible role. In a basis with diagonal upquark and Dirac-neutrino mass matrices it is assumed that the heavy neutrino mass matrix has only zero elements in its diagonal, in analogy to the light neutrino mass ma...