PLANCK SCALE EFFECTS IN NEUTRINO PHYSICS

We study the phenomenology and cosmology of the Majoron (flavon) model s of three active and one inert neutrino paying special attention to t he possible (almost) conserved generalization of the Zeldovich-Konopin ski-Mahmoud lepton charge. Using Planck scale physics effects which pr ovide the breaking of the lepton charge, we show how in this picture o ne can incorporate the solutions to some of the central issues in neut rino physics such as the solar and atmospheric neutrino puzzles and th e dark matter problem with the possible existence of a heavy (1-10 keV ) neutrino. These gravitational effects induce tiny Majorana mass term s for neutrinos and considerable masses for flavons. The cosmological demand for the sufficiently fast decay of flavons implies a lower limi t on the electron-neutrino mass in the ran of 0.1-1 eV.