Dependence of Electroweak Parameters on the Definition of the Top-Quark Mass

Abstract

The QCD corrections to electroweak parameters depend on the renormalization scheme and scales used to define the top-quark mass. We analyze these dependences for the W-boson mass predicted via Delta r to O(alpha alpha_s) and O(alpha alpha_s^2) in the on-shell and MS-bar schemes. These variations provide us with a hint on the magnitude of the unknown higher-order QCD effects and contribute to the theoretical error of the prediction.

Comments: 27 pages (Latex), 6 figures (uuencoded compressed tarred Postscript). Extended and updated version, which incorporates the recently calculated next-to-leading-order QCD corrections to Delta rho and Delta r