Effects of new physics to the the ρ–parameter in the supersymmetric standard model

The contribution to the ρ–parameter of the quark–Higgs sector of the supersymmetric standard model is computed non–perturbatively using the large–NF expansion for the case tanβ=0. 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 2v so that the cutoff scale is of the order of the electroweak scale. These non–universal 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 non–decoupling effects are analyzed.