Publication
Title
Determination of $\alpha_{s}$ using OPAL hadronic event shapes at $\sqrt{s}$ =91-209 GeV and resummed NNLO calculations
Author
Institution/Organisation
OPAL Collaboration
Abstract
 Hadronic event shape distributions from e(+)e(-) 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 re-summed next-to-leading-log-approximation terms (NNLO+NLLA). The combined NNLO result from all variables and centre-of-mass energies is alpha(S)(m(Z0)) = 0.1201 +/- 0.0008 (stat.) +/- 0.0013(exp.) +/- 0.0010(had.) +/- 0.0024(theo.) while the combined NNLO + NLLA result is alpha(S)(m(Z0)) = 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.
Language
English
Source (journal)
European physical journal : C : particles and fields. - Berlin
Publication
Berlin : 2011
ISSN
1434-6044
Volume/pages
71:9(2011), p. 1-21
Article Reference
1733
ISI
000295527700007
Medium
E-only publicatie
Full text (Publishers DOI)
Full text (open access)
UAntwerpen
 Faculty/Department Research group Publication type Subject Affiliation Publications with a UAntwerp address