Gauge Coupling Unification in Gauge-Higgs GUT: Theory and Phenomenology

TL;DR

This paper investigates gauge coupling unification within gauge-Higgs grand unification models in a slice of AdS$_5$, exploring their theoretical consistency and potential experimental signatures, and demonstrating unification feasibility with specific model parameters.

Contribution

It provides a comprehensive analysis of gauge coupling evolution in gauge-Higgs GUT models using Planck-brane correlators, including effects of bulk fields and brane masses, and assesses unification in a concrete SU(6) model.

Findings

Gauge couplings can unify in gauge-Higgs GUT models with moderate brane kinetic terms.

The method avoids common pitfalls by including bulk scalar, fermion, and gauge-boson effects.

LHC signatures of TeV-scale $X,Y$-like bosons are predicted as traces of grand unification.

Abstract

We present a concise survey of the running of gauge couplings in realistic models of gauge-Higgs grand unification in a slice of AdS$_5$ space and investigate their potential unification. Besides unifying the gauge groups of the Standard Model, these models can address various unresolved puzzles, such as the lightness of the Higgs boson and the strong hierarchies within fermion masses and mixings, as well as provide a common origin of the gauge symmetries and the sector that spontaneously breaks them. At the same time, they furnish interesting LHC signatures in the form of TeV-scale resonances of the $X,Y$-like bosons, providing a trace of the grand-unified group, accessible at low energies. Using the method of Planck-brane correlators allows us to evolve the couplings consistently from the electroweak scale up to the Planck scale, avoiding shortcomings of other frequently-used approaches and including the effects of bulk scalars, fermions, and gauge-bosons within a common framework. We thereby revisit, contrast, and supplement results in the literature, the latter for example by including brane masses and the gauge-Higgs vacuum expectation value. Moreover, in a phenomenology section, we apply our results to the concrete case of Georgi-Glashow-like unification with a SU(6) $\supset$ SU(5) symmetry in the 5D bulk, presenting a quantitative survey of the quality of unification. We find that grand unification is possible in such models in the presence of moderately large brane kinetic terms.