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A combination by the LEP QCD working group of alpha-s values derived from event shape variables at LEP : a contribution to the 10th high-energy international conference on quantum chromodynamics held in Montpellier, France in July 2003.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
<mark>Journal publication date</mark>07/2004
<mark>Journal</mark>Nuclear Physics B - Proceedings Supplements
Issue number1
Volume133
Number of pages8
Pages (from-to)13-20
Publication StatusPublished
<mark>Original language</mark>English

Abstract

The LEP QCD Working Group has produced a combination of αs values derived from event-shape distributions. The distributions are measured at scales below the mass of the Z boson up to 206 GeV. Values of αs are all extracted using the consistent application of O(αs2)+ NLLA predictions with the modified Log(R) matching scheme. A combined αs is obtained for each experiment and observable using at least two experiments in each case for energies above at ad above the mass of the Z boson. A consistent treatment and controlled breakdown is made of the sources of uncertainty on the input values. The combined best value for αs(MZ) = 0.11 ± 0.003 ± 0.003. The dominant uncertainty is theoretical, due to the effects of missing higher order contributions.