Improved predictions for top quark, lightest supersymmetric particle, and Higgs scalar masses

We estimate the top quark, lightest sparticle (LSP), and Higgs scalar masses within a supersymmetric grand unified framework in which tanβ≃${\mathit{m}}_{\mathit{t}}^0$/${\mathit{m}}_{\mathit{b}}^0$ and the electroweak symmetry is radiatively broken. The requirement that the calculated b quark mass lies close to its measured value, together with the cosmological constraint ${\mathrm{\Omega }}_{\mathrm{LSP}}$≊1, fixes the top quark mass to be ${\mathit{m}}_{\mathit{t}}$(${\mathit{m}}_{\mathit{t}}$)≊140–185 GeV. The LSP (of B-ino purity ≳ 98%) has a mass ∼200–350 GeV. In the scalar Higgs sector the CP-odd scalar mass ${\mathit{m}}_{\mathit{A}}$≲220 GeV. With ${\mathit{m}}_{\mathit{A}}$≳${\mathit{M}}_{\mathit{Z}}$, as suggested by the decay b→sγ, we find ${\mathit{M}}_{\mathit{Z}}$≲${\mathit{m}}_{\mathit{h}}^0$(${\mathit{m}}_{\mathit{H}}^0$)≲140(220) GeV and 120 GeV ≲${\mathit{m}}_{\mathit{H}}^{\pm }$≲240 GeV.