Measurement of αs with radiative hadronic events

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2008, Vol.53 (1), p.21-39, Article 21
• Main Authors: Ainsley, C., Åkesson, P.F., Alexander, G., Anderson, K.J., Asai, S., Barlow, R.J., Behnke, T., Bell, P.J., Bellerive, A., Bethke, S., Biebel, O., Bock, P., Boutemeur, M., Burckhart, H.J., Carter, J.R., Ciocca, C., Csilling, A., Dado, S., De Roeck, A., De Wolf, E.A., Dienes, B., Duckeck, G., Ferrari, P., Ford, M., Frey, A., Gagnon, P., Gary, J.W., Grunhaus, J., Gruwé, M., Hajdu, C., Hamann, M., Harel, A., Hawkes, C.M., Herten, G., Heuer, R.D., Hill, J.C., Igo-Kemenes, P., Karlen, D., Kellogg, R.G., Kluth, S., Kobel, M., Komamiya, S., Krämer, T., Lellouch, D., Levinson, L., Lloyd, S.L., Loebinger, F.K., Ludwig, A., Ludwig, J., Mashimo, T., Mättig, P., Meijers, F., Menges, W., Merritt, F.S., Michelini, A., Mihara, S., Miller, D.J., Mohr, W., Nagai, K., Nakamura, I., O’Neale, S.W., Oreglia, M.J., Pahl, C., Pásztor, G., Plane, D.E., Pooth, O., Przybycień, M., Rabbertz, K., Renkel, P., Roney, J.M., Rozen, Y., Sachs, K., Sarkisyan, E.K.G., Schaile, O., Schröder, M., Schumacher, M., Seuster, R., Shears, T.G., Sherwood, P., Smith, A.M., Söldner-Rembold, S., Stahl, A., Strom, D., Ströhmer, R., Tarem, S., Tasevsky, M., Trócsányi, Z., Tsur, E., Ueda, I., Vollmer, C.F., Verzocchi, M., Ward, C.P., Watkins, P.M., Wells, P.S., Wengler, T., Wermes, N., Wilson, J.A., Wolf, G., Wyatt, T.R., Zer-Zion, D.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics and Cosmology; Dependence; Elementary Particles; Hadrons; Heavy Ions; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Photons; Physics; Physics and Astronomy; Predictions; Quantum Field Theories; Quantum Field Theory; Regular Article - Experimental Physics; String Theory; Uncertainty analysis
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-007-0470-9

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 α 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 α s is studied. Our results are consistent with the running of α 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 α s (M Z )=0.1182±0.0015(stat.)±0.0101(syst.).