Gauge Coupling Unification with Extra Dimensions and Gravitational Scale Effects

TL;DR

This paper explores how gauge coupling unification can occur at TeV scales with extra dimensions, considering quantum gravitational effects and the implications for string theory and electroweak symmetry breaking.

Contribution

It demonstrates that unification at TeV scales is possible with extra dimensions and gravitational effects, challenging traditional high-scale unification models.

Findings

Unification can occur at TeV scales with extra dimensions.

Quantum gravitational effects can shift gauge couplings by a few percent.

Strongly coupled theories at TeV scales may induce electroweak symmetry breaking.

Abstract

We study gauge coupling unification in the presence of extra dimensions compactified at a few TeV. Achieving unification requires a large number of gauge boson Kaluza-Klein excitations lighter than the string scale, such that the higher-dimensional gauge couplings are O(1) in string scale units. Corrections to the gauge couplings from two or more loops are about 10% or larger, hence string (or M) theory is generally expected to be strongly coupled in TeV-scale extra-dimensional scenarios. Higher-dimensional operators induced by quantum gravitational effects can shift the gauge couplings by a few percent. These effects are sufficiently large that even the minimal Standard Model, or the MSSM, allow unification at a scale in the TeV range. The strongly coupled unified theory may induce dynamical electroweak symmetry breaking.