δT/T, Neutrino Oscillations And Proton Decay

A gauged U(1)B-L symmetry predicts three right handed handed neutrinos and its spontaneous breaking automatically yields the seesaw mechanism. In a supersymmetric setting this breaking can be nicely linked with inflation to yield δT/T proportional to (MB-L/MP)2, where MB-L (MP) denote the B - L breaking (Planck) scale respectively. Thus MB-L is estimated to be of order 1016 GeV, and the heaviest right handed neutrino mass is of order 1014 GeV. A second right handed neutrino turns out to have a mass of order 10 - 102 Tr, where Tr (< or approx. 1010 GeV) denotes the reheat temperature. A U(1) R symmetry plays an essential role in implementing inflation and leptogenesis, resolving the MSSM μ problem and eliminationg dimension five nucleon decay. An unbroken Z2 subgroup plays the role of matter parity. Extension to SO(10) is possible and implications for proton decay are briefly discussed