RADIATIVE ELECTROWEAK SYMMETRY-BREAKING IN THE MINIMAL SUPERSYMMETRICSTANDARD MODEL AND LOW-ENERGY THRESHOLDS

We study radiative electroweak symmetry breaking in the minimal supers ymmetric standard model (MSSM). We employ the two-loop renormalization group equations for running masses and couplings taking into account sparticle threshold effects. The decoupling of each particle below its threshold is realized by a step function in all one-loop renormalizat ion group equations. This program requires the calculation of all wave function, vertex, and mass renormalizations for all particles involve d. Adapting our numerical routines to take care of the succesive decou pling of each particle below its threshold, we compute the mass spectr um of sparticles and Higgs bosons consistent with the existing experim ental constraints. The effect of the threshold corrections is in gener al of the same order of magnitude as the two-loop contributions with t he exception of the heavy Higgs bosons and those neutralino and chargi no states that are nearly Higgsinos for large values of the parameter mu.