MPI für Physik / MPI für Physik |
|Determination of alphaS using OPAL hadronic event shapes at sqrts = 91-209 GeV and resummed NNLO calculations|
|Authors:||The OPAL Collaboration; Abbiendi, G.; et al.|
|Intended Educational Use:||No|
|Abstract / Description:||Hadronic event shape distributions from \epem\ annihilation|
measured by the OPAL experiment at centre-of-mass energies between 91~GeV and 209~GeV are used to determine the strong coupling alpha_S. The results are based on QCD predictions complete to the next-to-next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO+NLLA). The combined NNLO result from all variables and centre-of-mass energies is
alpha_S(MZ) = 0.1201 ± 0.0008(stat.) ± 0.0013(exp.) ± 0.0010(had.) ± 0.0024(theo.)
while the combined NNLO+NLLA result is
alpha_S(MZ) = 0.1189 ± 0.0008(stat.) ± 0.0016(exp.) ± 0.0010(had.) ± 0.0036(theo.).
The completeness of the NNLO and NNLO+NLLA results with respect to missing higher order contributions,
studied by varying the renormalization scale,
is improved compared to previous results based on NLO or NLO+NLLA predictions only. The observed energy dependence of alpha_S agrees with the QCD prediction of asymptotic freedom and excludes the absence of running.
|Classification / Thesaurus:||OPAL|
|Comment of the Author/Creator:||Submitted to Eur. Phys. J. C.|
|Affiliations:||MPI für Physik|
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