Measurement of alpha(s) with radiative hadronic events.

Abbiendi, G. and Ainsley, C. and Akesson, P. F. and Alexander, G. and Anagnostou, G. and Anderson, K. J. and Asai, S. and Axen, D. and Bailey, I. and Barberio, E. and Barillari, T. and Barlow, R. J. and Batley, R. J. and Bechtle, P. and Behnke, T. and Bell, K. W. and Bell, P. J. and Bella, G. and Bellerive, A. and Benelli, G. and Bethke, S. and Biebel, O. and Boeriu, O. and Bock, P. and Boutemeur, M. and Braibant, S. and Brown, R. M. and Burckhart, H. J. and Campana, S. and Capiluppi, P. and Carnegie, R. K. and Carter, A. A. and Carter, J. R. and Chang, C. Y. and Charlton, D. G. and Ciocca, C. and Csilling, A. and Cuffiani, M. and Dado, S. and Dallavalle, M. and De Roeck, A. and De Wolf, E. A. and Desch, K. and Dienes, B. and Dubbert, J. and Duchovni, E. and Duckeck, G. and Duerdoth, I. P. and Etzion, E. and Fabbri, F. and Ferrari, P. and Fiedler, F. and Fleck, I. and Ford, M. and Frey, A. and Gagnon, P. and Gary, J. W. and Geich-Gimbel, C. and Giacomelli, G. and Giacomelli, P. and Giunta, M. and Goldberg, J. and Gross, E. and Grunhaus, J. and Gruwe, M. and Gupta, A. and Hajdu, C. and Hamann, M. and Hanson, G. G. and Harel, A. and Hauschild, M. and Hawkes, C. M. and Hawkings, R. and Herten, G. and Heuer, R. D. and Hill, J. C. and Horvath, D. and Igo-Kemenes, P. and Ishii, K. and Jeremie, H. and Jovanovic, P. and Junk, T. R. and Kanzaki, J. and Karlen, D. and Kawagoe, K. and Kawamoto, T. and Keeler, R. K. and Kellogg, R. G. and Kennedy, B. W. and Kluth, S. and Kobayashi, T. and Kobel, M. and Komamiya, S. and Kraemer, T. and Krasznahorkay, A. and Krieger, P. and vonKrogh, J. and Kuhl, T. and Kupper, M. and Lafferty, G. D. and Landsman, H. and Lanske, D. and Lellouch, D. and Letts, J. and Levinson, L. and Lillich, J. and Lloyd, S. L. and Loebinger, F. K. and Lu, J. and Ludwig, A. and Ludwig, J. and Mader, W. and Marcellini, S. and Martin, A. J. and Mashimo, T. and Maettig, P. and McKenna, J. and McPherson, R. A. and Meijers, F. and Menges, W. and Merritt, F. S. and Mes, H. and Meyer, N. and Michelini, A. and Mihara, S. and Mikenberg, G. and Miller, D. J. and Mohr, W. and Mori, T. and Mutter, A. and Nagai, K. and Nakamura, I. and Nanjo, H. and Neal, H. A. and O'Neale, S. W. and Oh, A. and Oreglia, M. J. and Orito, S. and Pahl, C. and Pasztor, G. and Pater, J. R. and Pilcher, J. E. and Pinfold, J. and Plane, D. E. and Pooth, O. and Przybycien, M. and Quadt, A. and Rabbertz, K. and Rembser, C. and Renkel, P. and Roney, J. M. and Rossi, A. M. and Rozen, Y. and Runge, K. and Sachs, K. and Saeki, T. and Sarkisyan, E. K. G. and Schaile, A. D. and Schaile, O. and Scharff-Hansen, P. and Schieck, J. and Schoerner-Sadenius, T. and Schroeder, M. and Schumacher, M. and Seuster, R. and Shears, T. G. and Shen, B. C. and Sherwood, P. and Skuja, A. and Smith, A. M. and Sobie, R. and Soeldner-Rembold, S. and Spano, F. and Stahl, A. and Strom, D. and Stroehmer, R. and Tarem, S. and Tasevsky, M. and Teuscher, R. and Thomson, M. A. and Torrence, E. and Toya, D. and Trigger, I. and Trocsanyi, Z. and Tsur, E. and Turner-Watson, M. F. and Ueda, I. and Ujvari, B. and Vollmer, C. F. and Vannerem, P. and Vertesi, R. and Verzocchi, M. and Voss, H. and Vossebeld, J. and Ward, C. P. and Ward, D. R. and Watkins, P. M. and Watson, A. T. and Watson, N. K. and Wells, P. S. and Wengler, T. and Wermes, N. and Wilson, G. W. and Wilson, J. A. and Wolf, G. and Wyatt, T. R. and Yamashita, S. and Zer-Zion, D. and Zivkovic, L. and Collaboration, OPAL (2008) Measurement of alpha(s) with radiative hadronic events. European Physical Journal C: Particles and Fields, 53 (1). pp. 21-39. ISSN 1434-6044

Abstract

Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of the Z boson with the OPAL detector at LEP. The strong coupling alpha(s) is extracted by comparing data and QCD predictions for event shape observables at average reduced centre-of-mass energies ranging from 24 GeV to 78 GeV, and the energy dependence of alpha(s) is studied. Our results are consistent with the running of alpha(s) as predicted by QCD and show that within the uncertainties of our analysis event shapes in hadronic Z decays with hard and isolated photon radiation can be described by QCD at reduced centre-of-mass energies. Combining all values from different event shape observables and energies gives alpha(s)(M-Z)=0.1182 +/- 0.0015(stat.)+/- 0.0101(syst.).