Perturbative Unification and Higgs Boson Mass Bounds

TL;DR

This paper explores models extending the MSSM with new vector-like matter and a lateral gauge symmetry, allowing the Higgs boson mass upper limit to be increased to 200-300 GeV while preserving gauge coupling unification.

Contribution

It introduces a class of models with vector-like matter and a lateral gauge symmetry that relax the Higgs mass bound in supersymmetric theories while maintaining gauge unification.

Findings

Higgs mass upper bound can be increased to 200-300 GeV.

Models include new matter with SU(5) quantum numbers and a lateral SU(N) symmetry.

Perturbative Yukawa couplings up to the unification scale are achievable.

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 $m_h$ > 114 GeV. Here we show ways in which this upper limit on $m_h$ 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 (\kappa) to the usual Higgs doublet $H_u$. This new matter transforms non-trivially under a "lateral" SU(N) gauge symmetry, which enables the new Yukawa couplings \kappa to 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, $m_h$ can be raised to values as large as 200 - 300 GeV.