RADIATIVE ELECTROWEAK BREAKING AND SPARTICLE SPECTROSCOPY WITH TAN BETA-SIMILAR-OR-EQUAL-TO-MT/MB

We explore radiative electroweak breaking and the related issue of sparticle spectroscopy within an N=1 supergravity framework in which the Yukawa couplings h(t), h(b) and h(tau) are unified at the GUT scale. The parameter tan beta of the minimal supersymmetric standard model (MSSM) is constrained to lie close to m(t)/m(b) much greater than 1. With m(t)(m(t)) greater than or similar to 130 GeV, analysis based on the renormalization group improved tree level potential shows that in order to achieve a satisfactory radiative breaking, the universal gaugino mass M1/2 greater than or similar to 450 GeV. An upper bound on M1/2 of approximately 1250 GeV is obtained from cosmological considerations. This enables us to provide both lower and upper bounds on the sparticle masses of the MSSM. For 130 GeV less than or similar to m(t)(m(t)) less than or similar to 160 GeV, the lightest supersymmetric particle, essentially the bino, lies in the range 200 GeV less than or similar to m(LSP) less than or similar to 550 GeV. The heaviest sparticles include the gluino (1 TeV less than or similar to m(gBAR) less than or similar to 3.0 TeV) and the squarks of the first two families which typically are about (10-20)% heavier.