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Determination of the strong coupling constant using matched NNLO+NLLA predictions for hadronic event shapes in e+e− annihilations


Dissertori, G; Gehrmann-De Ridder, A; Gehrmann, T; Glover, E; Heinrich, G; Luisoni, G; Stenzel, H (2009). Determination of the strong coupling constant using matched NNLO+NLLA predictions for hadronic event shapes in e+e− annihilations. Journal of High Energy Physics, (8):036.

Abstract

We present a determination of the strong coupling constant from a fit of QCD predictions for six event-shape variables, calculated at next-to-next-to-leading order (NNLO) and matched to resummation in the next-to-leading-logarithmic approximation (NLLA). These event shapes have been measured in e+e− annihilations at LEP, where the data we use have been collected by the ALEPH detector at centre-of-mass energies between 91 and 206 GeV. Compared to purely fixed order NNLO fits, we observe that the central fit values are hardly affected, but the systematic uncertainty is larger because the NLLA part re-introduces relatively large uncertainties from scale variations. By combining the results for six event-shape variables and eight centre-of-mass energies, we find αs(MZ) = 0.1224 ± 0.0009 (stat) ± 0.0009 (exp) ± 0.0012 (had) ± 0.0035 (theo), which improves previously published measurements at NLO+NLLA. We also carry out a detailed investigation of hadronisation corrections, using a large set of Monte Carlo generator predictions.

Abstract

We present a determination of the strong coupling constant from a fit of QCD predictions for six event-shape variables, calculated at next-to-next-to-leading order (NNLO) and matched to resummation in the next-to-leading-logarithmic approximation (NLLA). These event shapes have been measured in e+e− annihilations at LEP, where the data we use have been collected by the ALEPH detector at centre-of-mass energies between 91 and 206 GeV. Compared to purely fixed order NNLO fits, we observe that the central fit values are hardly affected, but the systematic uncertainty is larger because the NLLA part re-introduces relatively large uncertainties from scale variations. By combining the results for six event-shape variables and eight centre-of-mass energies, we find αs(MZ) = 0.1224 ± 0.0009 (stat) ± 0.0009 (exp) ± 0.0012 (had) ± 0.0035 (theo), which improves previously published measurements at NLO+NLLA. We also carry out a detailed investigation of hadronisation corrections, using a large set of Monte Carlo generator predictions.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Uncontrolled Keywords:Jets; LEP HERA and SLC Physics; NLO Computations; QCD
Language:English
Date:2009
Deposited On:22 Feb 2010 11:48
Last Modified:05 Apr 2016 13:56
Publisher:Institute of Physics Publishing
ISSN:1029-8479
Publisher DOI:https://doi.org/10.1088/1126-6708/2009/08/036
Related URLs:http://arxiv.org/abs/0906.3436

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