EFFECTS OF NEW PHYSICS ON THE ρ PARAMETER IN THE SUPERSYMMETRIC STANDARD MODEL

Abstract

The contribution to the ρ parameter of the quark-Higgs sector of the supersymmetric standard model is computed nonperturbatively using the large-NF expansion. An explicit formula is found for the ρ parameter which is ill-defined unless the triviality cutoff is taken into account. The cutoff dependence of the ρ parameter is found to be large if and only if the top mass is larger than 2v1 so that the cutoff scale is of the order of the electroweak scale. These nonuniversal effects are the reflections at low energies of the physics beyond the supersymmetric standard model. By also considering the effects of the soft-breaking terms, cutoff effects in both decoupling and nondecoupling effects are analyzed.