Flipped SU(5) GUT Phenomenology: Proton Decay and $g_\mu-2$

TL;DR

This paper explores flipped SU(5) GUT models, analyzing proton decay and muon g-2, identifying parameter regions where proton decay might be observable and the muon g-2 discrepancy partially resolved.

Contribution

It demonstrates that relaxing universality constraints in flipped SU(5) models allows for simultaneous observable proton decay and a partial resolution of the muon g-2 anomaly.

Findings

Proton lifetime typically exceeds 10^{36} years in constrained models.

Detectable proton decay possible in certain parameter regions with large Higgs couplings.

Relaxing universality constraints enables significant contributions to g-2 while maintaining proton decay observability.

Abstract

We consider proton decay and $g_\mu - 2$ 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 $\gtrsim 10^{36}$~yrs, too long to be detected in the foreseeable future, and the supersymmetric contribution to $g_\mu - 2$ 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 $p \to e^+ \pi^0$ decay may be detectable in the Hyper-Kamiokande experiment now under construction, though the contribution to $g_\mu -2$ is still small. A substantial contribution to $g_\mu - 2$ 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 $g_\mu - 2$ discrepancy and acceptable values of $m_h$ and the relic LSP density.