Calculable upper limit on the mass of the lightest Higgs boson in perturbatively valid supersymmetric theories with arbitrary Higgs sectors

We derive a calculable upper limit on the mass of the lightest Higgs boson in perturbatively valid supersymmetric theories with arbitrary Higgs sectors. We assume a supersymmetry spectrum around or below 1 TeV and the standard model gauge symmetry, but place no restrictions on the Higgs sector. We estimate ${\mathit{m}}_{\mathit{h}}^0$<146 GeV for ${\mathit{M}}_{\mathit{t}}$≳100 GeV from all effects except possible additional heavy fermions beyond top (which could increase the limit approximately 12 GeV per extra family); for 60≲100 GeV we find ${\mathit{m}}_{\mathit{h}}^0$<156 GeV. In most explicitly constructed models the lightest Higgs boson mass does not saturate the upper limit.