Measurement of the strong coupling constant αs from global event-shape variables of hadronic Z decays

D. Decampo, B. Deschizeaux, C. Goy, J. P. Lees, M. N. Minard, R. Alemany, J. M. Crespo, M. Delfino, E. Fernandez, V. Gaitan, Ll Garrido, P. Mato, R. Miquel, Ll M. Mir, S. Orteu, A. Pacheco, J. A. Perlas, E. Tubau, M. G. Catanesi, D. CreanzaM. de Palma, A. Farilla, G. Iaselli, G. Maggi, M. Maggi, S. Natali, S. Nuzzo, M. Quattromini, A. Ranieri, G. Raso, F. Romano, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, G. Zito, Y. Gao, H. Hu, D. Huang, X. Huang, J. Lin, J. Lou, C. Qiao, T. Ruan, T. Wang, Y. Xie, D. Xu, R. Xu, J. Zhang, W. Zhao, H. Albrecht, W. B. Atwood, F. Bird, E. Blucher, G. Bonvicini, F. Bossi, D. Brown, T. H. Burnett, H. Drevermann, F. Dydak, R. W. Forty, C. Grab, R. Hagelberg, S. Haywood, B. Jost, M. Kasemann, G. Kellner, J. Knobloch, A. Lacourt, I. Lehraus, T. Lohse, D. Lüke, A. Marchioro, M. Martinez, J. May, S. Menary, A. Minten, A. Miotto, J. Nash, P. Palazzi, F. Ranjard, G. Redlinger, A. Roth, J. Rothberg, H. Rotscheidt, W. von Rüden, R. St.Denis, D. Schlatter, M. Takashima, M. Talby, W. Tejessy, H. Wachsmuth, S. Wasserbaech, S. Wheeler, W. Wiedenmann, W. Witzeling, J. Wotschack, Z. Ajaltouni, M. Bardadin-Otwinowska, A. Falvard

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53 Citations (Scopus)


An analysis of global event-shape variables has been carried out for the reaction e+e-→Z0→hadrons to measure the strong coupling constant αs. This study is based on 52 720 hadronic events obtained in 1989/90 with the ALEPH detector at the LEP collider at energies near the peak of the Z-resonance. In order to determine αs, second order QCD predictions modified by effects of perturbative higher orders and hadronization were fitted to the experimental distributions of event-shape variables. From a detailed analysis of the theoretical uncertainties we find that this approach is best justified for the differential two-jet rate, from which we obtain αs(MZ2) = 0.121 ± 0.002(stat.)±0.003(sys.)±0.007(theor.) using a renormalization scale ω = 1 2MZ. The dependence of αs(MZ2) on ω is parameterized. For scales mb<ω<MZ the result varies by -0.012+0.007. © 1991.
Original languageEnglish
Pages (from-to)623-633
JournalPhysics Letters B
Issue number4
Publication statusPublished - 21 Feb 1991


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