Higgs limit and b→sγ constraints in minimal supersymmetry

Abstract New limits on the Higgs mass from LEP and new calculations on the radiative (penguin) decay of the b-quark into sγ restrict the parameter space of the Constrained Minimal Supersymmetric Standard Model (CMSSM). We find that for the low tanβ scenario only one sign of the Higgs mixing parameter is allowed, while the high tanβ scenario is practically excluded, if one requires all sparticles to be below 1 TeV and imposes radiative electroweak symmetry breaking as well as gauge and Yukawa coupling unification. For squarks between 1 and 2 TeV high tanβ scenarios are allowed. We consider especially a new high tanβ=64 scenario with triple unification of all Yukawa couplings of the third generation, which shows an infrared fixed point behaviour. The upper limit on the mass of the lightest Higgs in the low (high) tanβ scenarios is 97±6 (120±2) GeV, where the largest error originates predominantly from the uncertainty in the top mass.