Eur. Phys. J. C (2009) 64: 351-360
https://doi.org/10.1140/epjc/s10052-009-1149-1

Regular Article - Experimental Physics

Determination of the strong coupling α_S from hadronic event shapes with and resummed QCD predictions using JADE data

¹ Max-Planck-Institut für Physik, Föhringer Ring 6, 80805, Munich, Germany
² Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, 85748, Garching, Germany

^* e-mail: skluth@mpp.mpg.de

Received: 7 October 2008
Published online: 13 October 2009

Abstract

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 α_S. 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 α_S agrees with the QCD prediction of asymptotic freedom and excludes absence of running with 99% confidence level.