Proton decay: flipped vs. unflipped SU(5)

A bstract 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 → π 0 μ + ) / Γ( p → π 0 e + ), Γ( p → π + ν ¯ ) / Γ( p → π 0 e + ), Γ( p → K 0 e + ) / Γ( p → π 0 e + ) and Γ( p → K 0 μ + ) / Γ( p → π 0 μ + ), and that predictions for the ratios Γ( p → π 0 μ + ) / Γ( p → π 0 e + ) and Γ( p → π + ν ¯ ) / Γ( p → π 0 e + ) 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.