First determination of the strong coupling constant using NNLO predictions for hadronic event shapes in e^+e^- annihilations
Abstract
We present the first determination of the strong coupling constant from a fit of next-to-next-to-leading order QCD predictions to event-shape variables, measured in annihilations at LEP. The data have been collected by the ALEPH detector at centre-of-mass energies between 91 and 206 GeV. Compared to results of next-to-leading order fits we observe that the central fit values are lower by about 10%, with considerably reduced scatter among the results obtained with different event-shape variables. The dominant systematic uncertainty from renormalization scale variations is reduced by a factor of two. By combining the results for several event-shape variables and centre-of-mass energies, we find \alpha_s(M_Z^2) = 0.1240+-0.0008(stat)+-0.0010(exp)+-0.0011(had)+-0.0029(theo).
Cite
@article{arxiv.0712.0327,
title = {First determination of the strong coupling constant using NNLO predictions for hadronic event shapes in e^+e^- annihilations},
author = {G. Dissertori and A. Gehrmann-De Ridder and T. Gehrmann and E. W. N. Glover and G. Heinrich and H. Stenzel},
journal= {arXiv preprint arXiv:0712.0327},
year = {2008}
}
Comments
25 pages, LaTeX, extended discussion of hadronization corrections, typos corrected