%0 Journal Article
%T Gauge Coupling Unification with Extra Dimensions and Gravitational Scale Effects
%A Hsin-Chia Cheng
%A Bogdan A. Dobrescu
%A Christopher T. Hill
%J Physics
%D 1999
%I arXiv
%R 10.1016/S0550-3213(99)00816-0
%X 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.
%U http://arxiv.org/abs/hep-ph/9906327v2