Maximum mixing in atmospheric neutrino oscillation, as well as vanishing of the MNS matrix element Ue3, are consequences of a 2-3 symmetry, under which the neutrino mass matrix is invariant under the interchange of second and third generation neutrinos. These predictions of the 2-3 symmetry are consistent with the results of Super-Kamiokande, K2K, and CHOOZ experiments. If the symmetry is exact...

A simple extension of the standard model is proposed in which all the three generations of neutrinos are Dirac particles and are naturally light. We then assume that the neutrino mass matrix is diagonal and degenerate, with a few eV mass to solve the dark matter problem. The self energy radiative corrections, however, remove this degeneracy and allow mixing of these neutrinos. The electroweak r...

In these two lectures I describe first the theory of neutrino mass and then discuss the implications of recent data (including 708–day data Super–Kamiokande data) which strongly indicate the need for neutrino conversions to account for the solar and atmospheric neutrino observations. I also mention the LSND data, which provides an intriguing hint. The simplest ways to reconcile all these data i...

We present a determination of the neutrino mass matrix which holds for values of the neutrinoless double beta decay effective mass mee larger than the neutrino mass differences. We find eight possible solutions and discuss for each one the corresponding neutrino mass eigenvalues and zero texture. A minimal structure of the perturbations to add to these zero textures to recover the full mass mat...

Astrophysical implications of neutrino mass and mixings are discussed. The status of solar and atmospheric neutrino problems, and recent developments concerning nuclear physics input to solar models and solar opacities are reviewed. Implications of neutrino mass and mixings in supernova dynamics are explored. The effects of supernova density fluctuations in neutrino propagation is described.

The relations between the effective Majorana mass of the electron neutrino, mee, responsible for neutrinoless double beta decay, and the neutrino oscillation parameters are considered. We show that for any specific oscillation pattern mee can take any value (from zero to the existing upper bound) for normal mass hierarchy and it can have a minimum for inverse hierarchy. This means that oscillat...

A possibility to search for a heavy isosinglet (sterile) neutrino using its decay mode νs → l + 2 jets in the S channel production pp → W ∗ +X → lνs +X in the CMS experiment is studied. The only assumption about the heavy neutrino is its nonzero mixing with νe or νμ. The corresponding CMS discovery potential expressed in terms of the heavy neutrino mass and the mixing parameter between the heav...

We present an analysis of the global neutrino oscillation data in terms of four-neutrino mass schemes. We find that the strong preference of oscillations into active neutrinos implied by the latest solar as well as atmospheric neutrino data allows to rule out (2+2) mass schemes, whereas (3+1) schemes are strongly disfavoured by shortbaseline experiments. Our analysis shows that four-neutrino os...

The absolute value of neutrino masses are very difficult to measure experimentally. On the other hand, mass differences between neutrino mass eigenstates, (m1,m2,m3), can be measured in neutrino oscillation experiments. Observations of atmospheric neutrinos suggest a squared mass difference of δm ≃ 3× 10 eV [1,2]. While there are still several viable solutions to the solar neutrino problem the ...

The three active light neutrinos are used to explain the neutrino oscillations. The inherently bi-large mixing neutrino mass matrix and the Fritzsch type, bi-small mixing charged lepton mass matrix are assumed. By requiring the maximal νμ − ντ mixing for the atmospheric neutrino problem and the masssquared difference approperiate for the almost maximal mixing solution to the solar neutrino prob...