Proton Decay Prediction in 5D Gauge-Higgs Unification

TL;DR

This paper predicts proton decay in 5D gauge-Higgs unification models, linking the decay rate to the top quark mass and suggesting future experiments could observe it if the top quark mass exceeds 172.5 GeV.

Contribution

It provides a general prediction of proton decay in gauge-Higgs unification models, connecting the decay process to the top quark mass and compactification scale.

Findings

Proton decay rate correlates with top quark mass.

Future Hyper-Kamiokande could detect decay if top mass > 172.5 GeV.

Proton decay suppressed by 5D Planck scale, linked to compactification.

Abstract

The Higgs boson mass and top quark mass imply that the Higgs quartic coupling vanishes around the scale of $10^9 - 10^{13}$ GeV, depending on the precise value of the top quark mass. The vanishing quartic coupling can be naturally addressed if the Higgs field originates from a 5-dimensional gauge field and the 5th dimension is compactified at the scale of the vanishing Higgs quartic coupling, which is a scenario based on gauge-Higgs unification. We present a general prediction of the scenario on the proton decay process $p \to \pi^0 e^+$. In many gauge-Higgs unification models, the 1st generation fermions are localized towards an orbifold fixed point in order to realize the realistic Yukawa couplings. Hence, four-fermion operators responsible for the proton decay can appear with a suppression of the 5-dimensional Planck scale (not the 4-dimensional Planck scale). Since the 5-dimensional Planck scale is connected to the compactification scale, we have a correlation between the proton partial decay width and the top quark mass. We show that the future Hyper-Kamiokande experiment may discover the proton decay if the top quark pole mass is larger than about 172.5 GeV.