Dependence of electroweak parameters on the definition of the top-quark mass

Electroweak parameters depend on the renormalization scheme (and scale) used to define the top-quark mass. We analyze this dependence in O(#alpha##alpha#_s) by comparing the evaluations in the on-shell and MS schemes. In the case of the W-boson mass predicted from #DELTA#r, we find that the two evaluations differ by not more than 4 MeV when the mass renormalization scale is identified with the top-quark mass. We study also the scale dependence of the MS result. These variations indicate the magnitude of unknown higher-order effects and contribute to the theoretical error of the predictions. (orig.)Available from TIB Hannover: RA 2999(94-036) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman