We examine the constraints on the MNS lepton mixing matrix from the present and future experimental data of the neutrino oscillation, tritium beta decay, and neutrinoless double beta decay for Majorana neutrinos. We show that the small mixing angle solutions for solar neutrino problem are disfavored for small averaged mass (〈mν〉) of neutrinoless double beta decay (≤ 0.01 eV) in the inverse neut...

A Majorana type of the neutrino mass matrix induces a class of lepton number violating processes. Cross sections of these reactions are given in terms of the neutrino mass matrix element, and a semi-realistic event rate is estimated. These processes provide mass and mixing parameters not directly accessible by the neutrino oscillation experiments. If these processes are discovered with a larger...

It is well known that Zee type neutrino mass matrix can derive bi-maximal neutrino mixing for three neutrinos. We give the reconciliation of this model with the gauge mediated supersymmetry breaking scenario, which naturally suppresses the large flavor changing neutral current and CP violation in the supersymmetric standard model. When the messenger fields have suitable B − L charges, the radia...

A theoretical structure that involves neutrino mass eigenstates at non relativistic as well as relativistic energies is presented. Using this framework, we find that if the particle X, with mass 33.9 MeV, of the KARMEN collaboration anomaly is identified with the third neutrino mass eigenstate, then the present limit of 23 MeV upper bound on the tau neutrino mass implies |Uτ3| < 0.82. Typeset u...

We suggest the possibility that the anomalies observed in the LSND experiment and the Gallium radioactive source experiments may be due to neutrino oscillations generated by a large squared-mass difference of about 20 − 30 eV. We consider the simplest 3+1 four-neutrino scheme that can accommodate also the observed solar and atmospheric neutrino oscillations. We show that, in this framework, the...

We argue that in order to provide a natural explanation of both neutrino mass hierarchies and large neutrino mixing angles, as required by the atmospheric neutrino data, a single right-handed neutrino must give the dominant contribution to the 23 block of the light effective neutrino matrix, and illustrate this mechanism in the framework of models with U(1) family symmetries. Sub-dominant contr...

Current data from the atmospheric and solar neutrino experiments are beautifully explained by oscillations among three active neutrino species . Another data in favor of neutrino oscillation has been obtained in the LSND experiment . Reconciliation of these experimental results requires three distinct mass-squared differences, implying the existence of a sterile neutrino νs. In the four-neutrin...

The seesaw enhancement of the bi-large mixings are discussed for the two zero textures of the neutrino mass matrix. There are no large mixings in both Dirac neutrino mass matrix mD and right-handed Majorana neutrino mass matrix MR, however, the bi-large mixing is realized via the seesaw mechanism. We present twelve sets of mD and MR for the seesaw enhancement and discuss the related phenomena, ...

We calculate the time delays of neutrinos emitted in gamma ray bursts due to the effects of neutrino mass and quantum gravity using a time dependent Hubble constant which can significantly change the naive results presented hitherto in the literature for large redshifts, and gives some sensitivity to the details of dark energy. We show that the effects of neutrino mass, quantum gravity and dark...