Regular Article - Experimental Physics
Determination of the strong coupling αS from hadronic event shapes with and resummed QCD predictions using JADE data
Max-Planck-Institut für Physik, Föhringer Ring 6, 80805, Munich, Germany
2 Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, 85748, Garching, Germany
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Published online: 13 October 2009
Event Shape Data from e+e− annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 GeV and 44 GeV are used to determine the strong coupling αS. QCD predictions complete to next-to-next-to-leading order (NNLO), alternatively combined with resummed next-to-leading-log-approximation (NNLO + NLLA) calculations, are used. The combined value from six different event shape observables at the six JADE centre-of-mass energies using the NNLO calculations is and with the NNLO + NLLA calculations the combined value is The stability of the NNLO and NNLO + NLLA results with respect to missing higher order contributions, studied by variations of the renormalisation scale, is improved compared to previous results obtained with NLO + NLLA or with NLO predictions only. The observed energy dependence of αS agrees with the QCD prediction of asymptotic freedom and excludes absence of running with 99% confidence level.
© Springer-Verlag, 2009