Measurement of heavy quark forward-backward asymmetries and average B mixing using leptons in hadronic Z decays

G. Abbiendi, C. Ainsley, P. F. Åkesson, G. Alexander, J. Allison, P. Amaral, G. Anagnostou, K. J. Anderson, S. Arcelli, S. Asai, D. Axen, G. Azuelos, I. Bailey, E. Barberio, R. J. Barlow, R. J. Batley, P. Bechtle, T. Behnke, K. W. Bell, P. J. BellG. Bella, A. Bellerive, G. Benelli, S. Bethke, O. Biebel, O. Boeriu, P. Bock, M. Boutemeur, S. Braibant, L. Brigliadori, R. M. Brown, K. Buesser, H. J. Burckhart, S. Campana, R. K. Carnegie, B. Caron, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, A. Csilling, M. Cuffiani, S. Dado, A. De Roeck, E. A. De Wolf, K. Desch, B. Dienes, M. Donkers, J. Dubbert, E. Duchovni, G. Duckeck, I. P. Duerdoth, E. Etzion, F. Fabbri, L. Feld, P. Ferrari, F. Fiedler, I. Fleck, M. Ford, A. Frey, A. Fürtjes, P. Gagnon, J. W. Gary, G. Gaycken, C. Geich-Gimbel, G. Giacomelli, P. Giacomelli, M. Giunta, J. Goldberg, E. Gross, J. Grunhaus, M. Gruwé, P. O. Günther, A. Gupta, C. Hajdu, M. Hamann, G. G. Hanson, K. Harder, A. Harel, M. Harin-Dirac, M. Hauschild, C. M. Hawkes, R. Hawkings, R. J. Hemingway, C. Hensel, G. Herten, R. D. Heuer, J. C. Hill, K. Hoffman, D. Horváth, P. Igo-Kemenes, K. Ishii, H. Jeremie, P. Jovanovic, T. R. Junk, N. Kanaya, J. Kanzaki, G. Karapetian, D. Karlen, K. Kawagoe, T. Kawamoto, R. K. Keeler, R. G. Kellogg, B. W. Kennedy, D. H. Kim, K. Klein, A. Klier, S. Kluth, T. Kobayashi, M. Kobel, S. Komamiya, L. Kormos, T. Krämer, P. Krieger, J. von Krogh, K. Kruger, T. Kuhl, M. Kupper, G. D. Lafferty, H. Landsman, D. Lanske, J. G. Layter, A. Leins, D. Lellouch, J. Letts, L. Levinson, J. Lillich, S. L. Lloyd, F. K. Loebinger, J. Lu, J. Ludwig, A. Macpherson, W. Mader, S. Marcellini, A. J. Martin, G. Masetti, T. Mashimo, P. Mättig, W. J. McDonald, J. McKenna, T. J. McMahon, R. A. McPherson, F. Meijers, W. Menges, F. S. Merritt, H. Mes, A. Michelini, S. Mihara, G. Mikenberg, D. J. Miller, S. Moed, W. Mohr, T. Mori, A. Mutter, K. Nagai, I. Nakamura, H. Nanjo, H. A. Neal, R. Nisius, S. W. O'Neale, A. Oh, A. Okpara, M. J. Oreglia, S. Orito, C. Pahl, G. Pásztor, J. R. Pater, G. N. Patrick, J. E. Pilcher, J. Pinfold, D. E. Plane, B. Poli, J. Polok, O. Pooth, M. Przybycien, A. Quadt, K. Rabbertz, C. Rembser, P. Renkel, J. M. Roney, S. Rosati, Y. Rozen, K. Runge, K. Sachs, T. Saeki, E. K.G. Sarkisyan, A. D. Schaile, O. Schaile, P. Scharff-Hansen, J. Schieck, T. Schörner-Sadenius, M. Schröder, M. Schumacher, C. Schwick, W. G. Scott, R. Seuster, T. G. Shears, B. C. Shen, P. Sherwood, G. Siroli, A. Skuja, A. M. Smith, R. Sobie, S. Söldner-Rembold, F. Spano, A. Stahl, K. Stephens, D. Strom, R. Ströhmer, S. Tarem, M. Tasevsky, R. J. Taylor, R. Teuscher, M. A. Thomson, E. Torrence, D. Toya, P. Tran, I. Trigger, Z. Trócsányi, E. Tsur, M. F. Turner-Watson, I. Ueda, B. Ujvári, C. F. Vollmer, P. Vannerem, R. Vértesi, M. Verzocchi, H. Voss, J. Vossebeld, D. Waller, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, P. S. Wells, T. Wengler, N. Wermes, D. Wetterling, G. W. Wilson, J. A. Wilson, G. Wolf, T. R. Wyatt, S. Yamashita, D. Zer-Zion, L. Zivkovic

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Abstract

A measurement of the forward-backward asymmetries of e+e - → bb̄ and e+e- → cc̄ events using electrons and muons produced in semileptonic decays of bottom and charm hadrons is presented. The outputs of two neural networks designed to identify b → ℓ- and c → ℓ+ decays are used in a maximum likelihood fit to a sample of events containing one or two identified leptons. The b and c quark forward-backward asymmetries at three centre-of-mass energies √s and the average B mixing parameter χ are determined simultaneously in the fit. Using all data collected by OPAL near the Z resonance, the asymmetries are measured to be: AFB bb̄ = (4.7 ± 1.8 ± 0.1)%, AFB cc̄ = (-6.8 ± 0.9)% at 〈√s〉 = 89.51 GeV, AFBbb̄ = (9.72 ± 0.42 ± 0.15)%, A FBcc̄ = (5.68 ± 0.54 ± 0.39)% at 〈√s〉 = 91.25 GeV, AFBbb̄ = (10.3 ± 1.5 ± 0.2)%, AFBcc̄ = (14.6 ± 2.0 ± 0.8)% at 〈√s〉 = 92.95 GeV. For the average B mixing parameter, a value of: χ = (13.12 ± 0.49 ± 0.42)% is obtained. In each case the first uncertainty is statistical and the second systematic. These results are combined with other OPAL measurements of the b and c forward-backward asymmetries, and used to derive a value for the effective electroweak mixing angle for leptons sin2θ eff of 0.23238 ± 0.00052.

Original languageEnglish
Pages (from-to)18-36
Number of pages19
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume577
Issue number1-2
DOIs
Publication statusPublished - Dec 18 2003

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ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Abbiendi, G., Ainsley, C., Åkesson, P. F., Alexander, G., Allison, J., Amaral, P., Anagnostou, G., Anderson, K. J., Arcelli, S., Asai, S., Axen, D., Azuelos, G., Bailey, I., Barberio, E., Barlow, R. J., Batley, R. J., Bechtle, P., Behnke, T., Bell, K. W., ... Zivkovic, L. (2003). Measurement of heavy quark forward-backward asymmetries and average B mixing using leptons in hadronic Z decays. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 577(1-2), 18-36. https://doi.org/10.1016/j.physletb.2003.10.022