Flipped SU(5) GUT phenomenology: proton decay and g_μ- 2

We consider proton decay and g_μ- 2 in flipped SU(5) GUT models. We first study scenarios in which the soft supersymmetry-breaking parameters are constrained to be universal at some high scale M_in above the standard GUT scale where the QCD and electroweak SU(2) couplings unify. In this case the proton lifetime is typically ≳ 10 ³⁶ years, too long to be detected in the foreseeable future, and the supersymmetric contribution to g_μ- 2 is too small to contribute significantly to resolving the discrepancy between the experimental measurement and data-driven calculations within the Standard Model. However, we identify a region of the constrained flipped SU(5) parameter space with large couplings between the 10- and 5-dimensional GUT Higgs representations where p→ e⁺π decay may be detectable in the Hyper-Kamiokande experiment now under construction, though the contribution to g_μ- 2 is still small. A substantial contribution to g_μ- 2 is possible, however, if the universality constraints on the soft supersymmetry-breaking masses are relaxed. We find a ‘quadrifecta’ region where observable proton decay co-exists with a (partial) supersymmetric resolution of the g_μ- 2 discrepancy and acceptable values of m_h and the relic LSP density.