Unification and Phenomenology of F-Theory GUTs with U(1)_PQ

TL;DR

This paper explores F-theory GUT models with an added U(1)_PQ symmetry, analyzing gauge coupling unification, threshold effects, and LHC phenomenology, proposing a framework that maintains unification while predicting distinctive sparticle spectra.

Contribution

It introduces a phenomenological framework for SU(5) F-theory GUTs with U(1)_PQ, studying unification constraints, threshold effects, and LHC signatures of gauge mediation scenarios.

Findings

Gauge coupling unification constrains KK mode thresholds.

Non-GUT multiplets can serve as gauge mediation messengers.

LHC signatures can distinguish this model from mGMSB.

Abstract

We undertake a phenomenological study of SU(5) F-theory GUT models with an additional U(1)_{PQ} symmetry. In such models, breaking SU(5) with hypercharge flux leads to the presence of non-GUT multiplets in the spectrum. We study the effect these have on the unification of gauge couplings, including two-loop running as well as low- and high-scale threshold corrections. We use the requirement of unification to constrain the size of thresholds from KK modes of SU(5) gauge and matter fields. Assuming the non-GUT multiplets play the role of messengers of gauge mediation leads to controlled non-universalities in the sparticle spectrum while maintaining grand unification, and we study the LHC phenomenology of this scenario. We find that the MSSM spectrum may become compressed or stretched out {by up to a factor of three} depending on the distribution of hypercharge flux. We present a set of benchmark points whose production cross-sections and decays we investigate, and argue that precision kinematic edge measurements will allow the LHC to distinguish between our model and mGMSB.