paper

On the Scale Uncertainties in the Decay

arXiv:hep-ph/9707482 · doi:10.1016/S0370-2693(97)01142-8

Abstract

We analyze the theoretical uncertainties in due to the choice of the high energy matching scale $μ_W=\ord(\mw)$ and the scale at which the running top quark mass is defined: $\mtb(μ_t)$. To this end we have repeated the calculation of the initial conditions confirming the final results of Adel and Yao and Greub and Hurth and generalizing them to include the dependences on and with . In the leading order the and uncertainties in turn out to be and respectively. We show analytically how these uncertainties are reduced after including next-to-leading QCD corrections. They amount to and respectively. Reanalyzing the uncertainties due to the scale $μ_b=\ord(m_b)$ we find that after the inclusion of NLO effects they amount to which is a factor 2/3 smaller than claimed in the literature. Including the uncertainties due to input parameters as well as the non-perturbative and corrections we find where the error is dominated by uncertainties in the input parameters. This should be compared with found by Chetyrkin et al. where the error is shared evenly between the scale and parametric uncertainties.

11 pages, Latex. The paper is updated by incorporating recently modified results of the literature that were used for the numerical evaluation of eq. (17). A term originally missing in eq. (22) is added

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