Proton decay: flipped vs. unflipped SU(5).

We analyze nucleon decay modes in a no-scale supersymmetric flipped SU(5) GUT model, and contrast them with the predictions for proton decays via dimension-6 operators in a standard unflipped supersymmetric SU(5) GUT model. We find that these GUT models make very different predictions for the ratios Γ(p → π0μ+)/Γ(p → π0e+), Γ(p → π + ν ¯ )/Γ(p → π0e+), Γ(p → K0e+)/Γ(p → π0e+) and Γ(p → K0μ+)/Γ(p → π0μ+), and that predictions for the ratios Γ(p → π0μ+)/Γ(p → π0e+) and Γ(p → π + ν ¯ )/Γ(p → π0e+) also differ in variants of the flipped SU(5) model with normal- or inverse-ordered light neutrino masses. Upcoming large neutrino experiments may have interesting opportunities to explore both GUT and flavour physics in proton and neutron decays. [ABSTRACT FROM AUTHOR]