期刊
EUROPEAN PHYSICAL JOURNAL C
卷 64, 期 3, 页码 351-360出版社
SPRINGER
DOI: 10.1140/epjc/s10052-009-1149-1
关键词
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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 alpha(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 alpha(S)(m(Z0)) = 0.1210 +/- 0.0007(stat.) +/- 0.0021(exp.) +/- 0.0044(had.) +/- 0.0036(theo.) and with the NNLO + NLLA calculations the combined value is alpha(S)(m(Z0)) = 0.1172 +/- 0.0006(stat.) +/- 0.0020(exp.) +/- 0.0035(had.) +/- 0.0030(theo.). 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 alpha(S) agrees with the QCD prediction of asymptotic freedom and excludes absence of running with 99% confidence level.
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