Mass of Electron-Neutrino and SN1987A Data

By using a fresh analysis of SN1987A data it is shown that mass of the electron neutrino is zero. The masses of other neutrino flavors are found to be non-zero. The neutrino astrophysics has been the subject of great interest for the last many decades. Since it was postulated in 1930, the properties of neutrino and in particular the question of its mass have gained much attention on both theoretical and experimental fronts. By achieving high precision techniques, the upper limit on the electron-neutrino mass has dropped by a factor of 10, raising the question that whether neutrinos are truly massive or massless like photons [1]. In the past few years a variety of experiments involving atmospheric [2-4], solar [5-11], reactor [12,13] and accelerator [14,15] neutrinos have demonstrated that neutrinos disappear while traveling from the source to the detector. This behavior of neutrinos is considered to be consistent with the oscillation hypothesis that implies non-vanishing neutrino masses and a mixing matrix in analogy with the CKM matrix in the quark sector [16,17]. Thus the neutrino oscillation experiments have provided the first compelling evidence of its kind for physics beyond the standard model. So far, this model along with its strong predictive power has been providing excellent description of enormous experimental data [18,19]. The prominent feature of the oscillation data is three flavor mixing framework with large mixing angles [20]. The neutrino flavor eigenstates produced via weak interaction decays can be treated as linear combinations of mass eigenstates and the wave function of any neutrino flavor can be expanded in terms of wave functions of mass eigenstates. Since different mass eigenstates move with different speeds, the original flavor eigenstate possess a probability of being detected as an electron neutrino, a muon neutrino or a tau neutrino. The oscillation experiments suggest only mass-squared differences and the