Mass of the Lightest Higgs Boson in the Minimal Supersymmetric Standard Model with an Additional Singlet

Abstract

An upperbound on the mass of the lightest neutral scalar Higgs boson is calculated in an extended version of the minimal supersymmetric standard model that contains an additional Higgs singlet. We integrate the renormalization group equations of the model, and impose low energy boundary conditions consistent with present experimental results, and ultra-violet conditions following from triviality. Radiative corrections induced by a large top quark Yukawa coupling are included in our analysis, and we find the allowed values for the mass of the Higgs boson as a function of the mass of the top quark. Typically, for a top quark mass $m_t=150\ GeV$, the upper bound on the Higgs boson mass is about $25 \ GeV$ higher than in the minimal model.