alphas(MZ) from Jade Event Shapes
Abstract
Event shape data from e+e- annihilation into hadrons collected by the JADE experiment between sqrt(s)=14 and 44 GeV are used to determine the strong coupling alphaS. QCD predictionscomplete to next-to-next-to-leading order (NLLO), alternatively combined with next-to-leading-log-approximation (NLLA) are used. The stability of the NNLO and NNLO+NLLA results with respect to variations of the renormalisation scale is improved compared to previous results obtained with next-to-leading-order (NLO) or NLO+NLLA predictions. The energy dependence of alphaS agrees with the QCD prediction of asymptotic freedom and excludes absence of running with 99% confidence level.
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