Unification with Enlarged Kaluza-Klein Dimensions

TL;DR

This paper investigates how adding extra states in theories with enlarged Kaluza-Klein dimensions can achieve gauge coupling unification consistent with experimental data, addressing issues in minimal models with low-scale extra dimensions.

Contribution

It systematically analyzes the impact of additional states above the compactification scale on gauge coupling running, demonstrating new unification scenarios in both supersymmetric and nonsupersymmetric models.

Findings

Identified simple models achieving consistent unification with low-energy data.

Showed that extra states can correct large predictions of alpha_3(M_Z).

Provided examples of theories with enlarged dimensions that unify couplings.

Abstract

In minimal theories with extra spatial dimensions at scales mu_0 much lower than the conventional GUT scale, unification can give too-large predictions for alpha_3(M_Z) given alpha_1(M_Z) and alpha_2(M_Z) as empirical input. We systematically study the effects of adding extra states above the compactification scale on running of the gauge couplings and find several simple examples that give unification where all alpha_i(M_Z) are consistent with low-energy data. We study both the supersymmetric and nonsupersymmetric unification.