Perturbative Unification and Higgs Boson Mass Bounds
arXiv:hep-ph/0410085
Abstract
Supersymmetric extensions of the Standard Model generally give a theoretical upper limit on the lightest Higgs boson mass which may be uncomfortably close to the current experimental lower bound of > 114 GeV. Here we show ways in which this upper limit on can be relaxed substantially in the perturbative regime, while maintaining the successful unification of gauge couplings as observed in the minimal scenario. A class of models is presented, which includes new vector-like matter with the quantum numbers of the 5, 5-bar and singlet representations of SU(5) and having Yukawa couplings (κ) to the usual Higgs doublet . This new matter transforms non-trivially under a "lateral" SU(N) gauge symmetry, which enables the new Yukawa couplings κto be sizable, even larger than the top-quark Yukawa coupling, and still be perturbative at all momenta up to the unification scale of 10^{16} GeV. We find that, consistent with low energy constraints, can be raised to values as large as 200 - 300 GeV.
15 pages LaTeX, 4 EPS figures. References added