We consider phenomenologically allowed structures of the neutrino mass matrix in the case of three light neutrino species. Constraints from the solar, atmospheric and reactor neutrino experiments as well as those from the neutrinoless double beta decay are taken into account. Both hierarchical and quasi-degenerate neutrino mass cases are studied. Assuming maximal νμ − ντ mixing we derive simple...

We examine the prospects for determining the neutrino mixing matrix and for observing CP and T violation in neutrino oscillations in four-neutrino models. We focus on a general class of four-neutrino models with two pairs of nearly degenerate mass eigenstates separated by approximately 1 eV, which can describe the solar, atmospheric and LSND neutrino data. We present a general parametrization o...

The neutrino mass problem in SU(4) × SU(2)L × SU(2)R SUSY GUT obtained from the compactification of E8 × E8 heterotic string is analyzed. The estimated values of the neutrino masses and mixing angles can explain the experimental data on solar neutrino flux. Yerevan Physics Institute Yerevan 1995 Recent solar neutrino experiments give an evidence for nonzero neutrino masses. The solar neutrino d...

Assuming three-neutrino mixing and massive Majorana neutrinos, we study the implications of the neutrino oscillation solutions of the solar and atmospheric neutrino problems and of the results of the CHOOZ experiment for the predictions of the effective Majorana mass in neutrinoless double beta ((ββ) 0ν-)decay, |< m >|. The general case of CP-nonconservation is investigated. The predicted value...

We examine the prospects for determining the neutrino mixing matrix and for observing CP and T violation in neutrino oscillations in four-neutrino models. We focus on a general class of four-neutrino models with two pairs of nearly degenerate mass eigenstates separated by approximately 1 eV, which can describe the solar, atmospheric and LSND neutrino data. We present a general parametrization o...

Recently, many authors showed that if the solar and atmospheric neutrino data are both described by maximal mixing vacuum oscillations at the relevant mass scale, then there exists a unique bi-maximal lepton mixing matrix for three neutrino flavors. We construct the lepton mass matrices from the symmetry principle so that maximal mixings for the atmospheric and the solar neutrino vacuum oscilla...

Assuming three-neutrino mixing and massive Majorana neutrinos, we study the implications of the neutrino oscillation solutions of the solar and atmospheric neutrino problems and of the results of the CHOOZ experiment for the predictions of the effective Majorana mass in neutrinoless double beta ((ββ) 0ν-)decay, |< m >|. The general case of CP-nonconservation is investigated. The predicted value...

We study the effects of neutrino oscillation on supernova neutrino in the case of the inverted mass hierarchy (m3 ≪ m1 < m2) as well as the normal mass hierarchy (m1 < m2 ≪ m3). Numerical analysis using a realistic supernova and presupernova model allows us to discuss quantitatively a possibility to probe neutrino oscillation parameters. We show that information about the mass hierarchy can be ...