Proton Decay: Flipped vs Unflipped SU(5)

Abstract

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 $\Gamma (p\to {\pi }^0{\mu }^{+})/\Gamma (p\to {\pi }^0{e}^{+})$, $\Gamma (p\to {\pi }^{+}\bar{\nu })/\Gamma (p\to {\pi }^0{e}^{+})$, $\Gamma (p\to K^0{e}^{+})/\Gamma (p\to {\pi }^0{e}^{+})$ and $\Gamma (p\to K^0{\mu }^{+})/\Gamma (p\to {\pi }^0{\mu }^{+})$, and that predictions for the ratios $\Gamma (p\to {\pi }^0{\mu }^{+})/\Gamma (p\to {\pi }^0{e}^{+})$ and $\Gamma (p\to {\pi }^{+}\bar{\nu })/\Gamma (p\to {\pi }^0{e}^{+})$ 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.

Comments: 25 pages, 4 figures