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alpha_s(MZ) from Jade Event Shapes

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 نشر من قبل Stefan Kluth
 تاريخ النشر 2009
  مجال البحث
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 تأليف S. Kluth




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

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254 - C. Pahl , S. Kluth , S. Bethke 2004
Data from e+e- annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 GeV and 44 GeV were used to study moments of event shape distributions. The data were compared with Monte Carlo models and with prediction s from QCD NLO order calculations. The strong coupling constant measured from the moments is alpha_S(M_Z) = 0.1286 +/- 0.0007 (stat) +/- 0.0011 (expt) +/- 0.0022 (had) +/- 0.0068 (theo), alpha_S(M_Z) = 0.1286 +/- 0.0072 (total error), consistent with the world average. However, systematic deficiencies in the QCD NLO order predictions are visible for some of the higher moments.
162 - S. Bethke , S. Kluth , C. Pahl 2010
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 or der (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 $alpha_S(M_Z)$= 0.1210 +/- 0.0007(stat.) +/- 0.0021(expt.) +/- 0.0044(had.) +/- 0.0036(theo.) and with the NNLO+NLLA calculations the combined value is $alpha_S$= 0.1172 +/- 0.0006(stat.) +/- 0.0020(expt.) +/- 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.
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 study the four-jet event production rate as a function of the Durham jet algorithms resolution parameter ycut. The four-jet rate is compared to QCD next-to-leading order calculations including resummation of large logarithms in the next-to-leading logarithmic approximation. The strong coupling measured from the four-jet rate is as(MZ)=0.1159+-0.0004(stat)+-0.0012(expt)+-0.0024(had)+-0.0007(theo) in agreement with the world average.
69 - Stefan Kluth 2012
We describe a measurement of the strong coupling alpha_S(m_Z) from the 3-jet rate in hadronic final states of e+e- annihilation recorded with the JADE detector at centre-of-mass energies of 14 to 44 GeV. The jets are reconstructed with the Durham jet clustering algorithm. The JADE 3-jet rate data are compared with QCD predictions in NNLO combined with resummed NNLA calculations. We find good agreement between the data and the prediction and extract alpha_S(m_Z)= 0.1199 +/- 0.0010(stat.) +/- 0.0021(exp.) +/- 0.0054(had.) +/- 0.0007(theo.).
151 - J. Schieck , S. Kluth , S. Bethke 2004
Data from e+e- annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 GeV and 44 GeV were used to study the four-jet rate as a function of the Durham algorithms resolution parameter y_cut. The four-jet rate w as compared to a QCD NLO order calculations including NLLA resummation of large logarithms. The strong coupling constant measured from the four-jet rate is alpha_S(M_Z) = 0.1169 +/- 0.0004 (stat) +/- 0.0012 (expt) +/- 0.0021 (had) +/- 0.0007 (theo), alpha_S(M_Z) = 0.1169 +/- 0.0026 (total error) in agreement with the world average.
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