Unification of gauge couplings and the tau-neutrino mass in supergravity without R parity
Minimal R-parity violating supergravity predicts a value for alphas(MZ) smaller than in the case with conserved R-parity, and therefore closer to the experimental world average. We show that the R-parity violating effect on the alphas prediction comes from the larger two-loop b-quark Yukawa contribution to the renormalization group evolution of the gauge couplings which characterizes R-parity violating supergravity. The effect is correlated to the tau neutrino mass and is sensitive to the initial conditions on the soft supersymmetry breaking parameters at the unification scale. We show how a few percent effect on alphas(MZ) may naturally occur even with tau neutrino masses as small as indicated by the simplest neutrino oscillation interpretation of the atmospheric neutrino data from Super-Kamiokande.
Díaz, Marco Aurelio Ferrandis Alapont, Francisco Javier Romao, J. C. Furtado Valle, José Wagner 2000 Unification of gauge couplings and the tau-neutrino mass in supergravity without R parity Nuclear Physics B 590 1-2 3 18