On the role of the quark mass thresholds in extrapolations of the running α_s

Abstract

The accuracy of the conventional treatment of quark mass thresholds in the QCD running coupling constant ${\alpha }_s$, based on the step approximation to the $\beta$--function, is investigated. The errors of extrapolating $\ase(μ)$ from low energies to $\mu =M_Z$, implied by this approximation, are shown to be of the same magnitude as the typical next--to--next--to--leading order contributions to \as and tend to increase the resulting \as. The importance of the proper choice of matching points is emphasized.

latex, 7 pages, 2 uuencoded figures

References in corpus (2)

• The alpha_s^3 correction to Gamma (Z^0 -> hadrons)
• Mass Dependent ${\alpha }_S$ Evolution and the Light Gluino Existence

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• A mass-dependent beta-function
• The uncertainty in ${\alpha }_s(M_Z^2)$ determined from hadronic tau decay measurements
• Quasiconformality and mass