Measurement of Ab FBusing inclusive b-hadron decays

Based on a sample of four million events collected by ALEPH from 1991 to 1995, a measurement of the forward-backward asymmetry in Z → bb̄ decays using inclusive final states is presented. High-performance tagging of bb̄ events in a wide angular range is achieved using neural network techniques. An optimal hemisphere charge estimator is built by merging primary and secondary vertex information, leading kaon identification and jet charge in a neural network. The average charge asymmetry, the flavour tagging efficiencies and mean b-hemisphere charges are measured from data and used to extract the pole b asymmetry in the Standard Model A 0,b FB = 0.1009 ± 0.0027 (stat) ± 0.0012 (syst) , corresponding to a value of the effective weak mixing angle of sinθ W = 0.23193 ± 0.00056 . submitted to Eur. Phys. J. C The ALEPH Collaboration A. Heister, S. Schael Physikalisches Institut das RWTH-Aachen, D-52056 Aachen, Germany R. Barate, I. De Bonis, D. Decamp, C. Goy, J.-P. Lees, E. Merle, M.-N. Minard, B. Pietrzyk Laboratoire de Physique des Particules (LAPP), INP-CNRS, F-74019 Annecy-le-Vieux Cedex, France S. Bravo, M.P. Casado, M. Chmeissani, J.M. Crespo, E. Fernandez, M. Fernandez-Bosman, Ll. Garrido, E. Graugés, M. Martinez, G. Merino, R. Miquel, Ll.M. Mir, A. Pacheco, H. Ruiz Institut de Física d’Altes Energies, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain A. Colaleo, D. Creanza, M. de Palma, G. Iaselli, G. Maggi, M. Maggi, S. Nuzzo, A. Ranieri, G. Raso, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, A. Tricomi, G. Zito Dipartimento di Fisica, INFN Sezione di Bari, I-70126 Bari, Italy X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao Institute of High Energy Physics, Academia Sinica, Beijing, The People’s Republic of China D. Abbaneo, P. Azzurri, G. Boix, O. Buchmüller, M. Cattaneo, F. Cerutti, B. Clerbaux, G. Dissertori, H. Drevermann, R.W. Forty, M. Frank, T.C. Greening, J.B. Hansen, J. Harvey, P. Janot, B. Jost, M. Kado, P. Mato, A. Moutoussi, F. Ranjard, L. Rolandi, D. Schlatter, O. Schneider, W. Tejessy, F. Teubert, E. Tournefier, J. Ward European Laboratory for Particle Physics (CERN), CH-1211 Geneva 23, Switzerland Z. Ajaltouni, F. Badaud, A. Falvard, P. Gay, P. Henrard, J. Jousset, B. Michel, S. Monteil, J-C. Montret, D. Pallin, P. Perret, F. Podlyski Laboratoire de Physique Corpusculaire, Université Blaise Pascal, INP-CNRS, Clermont-Ferrand, F-63177 Aubière, France J.D. Hansen, J.R. Hansen, P.H. Hansen, B.S. Nilsson, A. Wäänänen Niels Bohr Institute, DK-2100 Copenhagen, Denmark A. Kyriakis, C. Markou, E. Simopoulou, A. Vayaki, K. Zachariadou Nuclear Research Center Demokritos (NRCD), GR-15310 Attiki, Greece A. Blondel, G. Bonneaud, J.-C. Brient, A. Rougé, M. Rumpf, M. Swynghedauw, M. Verderi, H. Videau Laboratoire de Physique Nucléaire et des Hautes Energies, Ecole Polytechnique, INP-CNRS, F-91128 Palaiseau Cedex, France V. Ciulli, E. Focardi, G. Parrini Dipartimento di Fisica, Università di Firenze, INFN Sezione di Firenze, I-50125 Firenze, Italy A. Antonelli, M. Antonelli, G. Bencivenni, G. Bologna, F. Bossi, P. Campana, G. Capon, V. Chiarella, P. Laurelli, G. Mannocchi, F. Murtas, G.P. Murtas, L. Passalacqua, M. Pepe-Altarelli, P. Spagnolo Laboratori Nazionali dell’INFN (LNF-INFN), I-00044 Frascati, Italy A.W. Halley, J.G. Lynch, P. Negus, V. O’Shea, C. Raine, A.S. Thompson Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ,United Kingdom S. Wasserbaech Department of Physics, Haverford College, Haverford, PA 19041-1392, U.S.A. R. Cavanaugh, S. Dhamotharan, C. Geweniger, P. Hanke, G. Hansper, V. Hepp, E.E. Kluge, A. Putzer, J. Sommer, K. Tittel, S. Werner, M. Wunsch Kirchhoff-Institut für Physik, Universität Heidelberg, D-69120 Heidelberg, Germany R. Beuselinck, D.M. Binnie, W. Cameron, P.J. Dornan, M. Girone, N. Marinelli, J.K. Sedgbeer, J.C. Thompson Department of Physics, Imperial College, London SW7 2BZ, United Kingdom V.M. Ghete, P. Girtler, E. Kneringer, D. Kuhn, G. Rudolph Institut für Experimentalphysik, Universität Innsbruck, A-6020 Innsbruck, Austria E. Bouhova-Thacker, C.K. Bowdery, A.J. Finch, F. Foster, G. Hughes, R.W.L. Jones, M.R. Pearson, N.A. Robertson Department of Physics, University of Lancaster, Lancaster LA1 4YB, United Kingdom I. Giehl, K. Jakobs, K. Kleinknecht, G. Quast, B. Renk, E. Rohne, H.-G. Sander, H. Wachsmuth, C. Zeitnitz Institut für Physik, Universität Mainz, D-55099 Mainz, Germany A. Bonissent, J. Carr, P. Coyle, O. Leroy, P. Payre, D. Rousseau, M. Talby Centre de Physique des Particules, Université de la Méditerranée, INP-CNRS, F-13288 Marseille, France M. Aleppo, F. Ragusa Dipartimento di Fisica, Università di Milano e INFN Sezione di Milano, I-20133 Milano, Italy A. David, H. Dietl, G. Ganis, K. Hüttmann, G. Lütjens, C. Mannert, W. Männer, H.-G. Moser, R. Settles, H. Stenzel, W. Wiedenmann, G. Wolf Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, D-80805 München, Germany J. Boucrot, O. Callot, M. Davier, L. Duflot, J.-F. Grivaz, Ph. Heusse, A. Jacholkowska, J. Lefrançois, J.-J. Veillet, I. Videau, C. Yuan Laboratoire de l’Accélérateur Linéaire, Université de Paris-Sud, INP-CNRS, F-91898 Orsay Cedex, France G. Bagliesi, T. Boccali, G. Calderini, L. Foà, A. Giammanco, A. Giassi, F. Ligabue, A. Messineo, F. Palla, G. Sanguinetti, A. Sciabà, G. Sguazzoni, R. Tenchini, A. Venturi, P.G. Verdini Dipartimento di Fisica dell’Università, INFN Sezione di Pisa, e Scuola Normale Superiore, I-56010 Pisa, Italy G.A. Blair, G. Cowan, M.G. Green, T. Medcalf, A. Misiejuk, J.A. Strong, P. Teixeira-Dias, J.H. von Wimmersperg-Toeller Department of Physics, Royal Holloway & Bedford New College, University of London, Egham, Surrey TW20 OEX, United Kingdom R.W. Clifft, T.R. Edgecock, P.R. Norton, I.R. Tomalin Particle Physics Dept., Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 OQX, United Kingdom B. Bloch-Devaux, P. Colas, S. Emery, W. Kozanecki, E. Lançon, M.-C. Lemaire, E. Locci, P. Perez, J. Rander, J.-F. Renardy, A. Roussarie, J.-P. Schuller, J. Schwindling, A. Trabelsi, B. Vallage CEA, DAPNIA/Service de Physique des Particules, CE-Saclay, F-91191 Gif-sur-Yvette Cedex, France N. Konstantinidis, A.M. Litke, G. Taylor Institute for Particle Physics, University of California at Santa Cruz, Santa Cruz, CA 95064, USA C.N. Booth, S. Cartwright, F. Combley, M. Lehto, L.F. Thompson Department of Physics, University of Sheffield, Sheffield S3 7RH, United Kingdom K. Affholderbach, A. Böhrer, S. Brandt, C. Grupen, A. Ngac, G. Prange, U. Sieler Fachbereich Physik, Universität Siegen, D-57068 Siegen, Germany

P. G. Verdini | M. P. Casado | J. Hansen | P. Azzurri | J. Nielsen | A. Litke | K. Cranmer | G. Sanguinetti | L. Mir | N. Robertson | P. Elmer | R. Miquel | G. Merino | M. Davier | D. Rousseau | S. Dhamotharan | G. Dissertori | A. Giassi | M. Antonelli | A. Blondel | E. Bouhova-Thacker | G. Calderini | F. Cerutti | L. Duflot | C. Geweniger | C. Goy | J. Grivaz | P. Hanke | P. Hansen | G. Hughes | K. Jakobs | S. Jin | R. Jones | M. Kado | K. Kleinknecht | E. Kluge | E. Kneringer | N. Konstantinidis | W. Kozanecki | D. Kuhn | P. Laurelli | P. Norton | V. O’Shea | Q. Ouyang | D. Pallin | F. Podlyski | F. Ragusa | J. Rothberg | G. Rudolph | J. Schwindling | H. Stenzel | J. Strong | M. Talby | P. Teixeira-Dias | W. Wiedenmann | C. Zeitnitz | G. Zobernig | O. Schneider | G. Raso | R. Barate | S. Schael | A. Giammanco | V. Chiarella | Mario Martínez | S.L. Wu | Xin Wu | B. Clerbaux | E. Locci | J. Rander | G. Quast | A. Kyriakis | C. Markou | A. Colaleo | D. Creanza | M. Palma | G. Iaselli | G. Maggi | M. Maggi | S. Nuzzo | G. Selvaggi | L. Silvestris | G. Zito | A. Tricomi | V. Ciulli | E. Focardi | G. Sguazzoni | G. Bagliesi | T. Boccali | F. Ligabue | A. Messineo | F. Palla | P. Spagnolo | R. Tenchini | A. Venturi | A. David | D. Abbaneo | J. Harvey | P. Janot | I. Tomalin | R. Beuselinck | O. Buchmuller | A. Heister | S. Wasserbaech | R. Cavanaugh | N. Marinelli | F. Badaud | M. Girone | H. Moser | T. Wang | Jinlong Zhang | D. Decamp | M. Minard | B. Pietrzyk | F. Teubert | Z. Ajaltouni | B. Michel | Y. Xie | J. Hansen | E. Grauges | P. Colas | C. Yuan | C. Grupen | R. Settles | A. Rougé | H. Videau | J. Brient | I. Bonis | J. M. Crespo | E. Fernández | M. Fernandez-Bosman | L. Garrido | A. Pacheco | A. Ranieri | F. Ruggieri | P. Tempesta | H. Hu | R. Xu | W. Zhao | H. Drevermann | R. Forty | G. Ganis | P. Mato | F. Ranjard | L. Rolandi | D. Schlatter | W. Tejessy | H. Wachsmuth | A. Falvard | J. Jousset | J. Montret | P. Perret | J. D. Hansen | B. Nilsson | E. Simopoulou | A. Vayaki | K. Zachariadou | G. Bonneaud | M. Rumpf | M. Verderi | G. Parrini | A. Antonelli | G. Bencivenni | G. Bologna | F. Bossi | P. Campana | G. Capon | G. Mannocchi | F. Murtas | G. Murtas | L. Passalacqua | M. Pepe-Altarelli | J. Lynch | C. Raine | A. Thompson | V. Hepp | A. Putzer | K. Tittel | M. Wunsch | W. Cameron | M. Cattaneo | A. Moutoussi | J. Sedgbeer | P. Girtler | A. Finch | F. Foster | B. Renk | A. Bonissent | J. Carr | P. Coyle | P. Payre | H. Dietl | A. Halley | G. Lütjens | G. Wolf | J. Boucrot | O. Callot | P. Heusse | J. Veillet | I. Videau | M. Green | T. Medcalf | R. Clifft | T. Edgecock | B. Bloch-Devaux | S. Emery | M. Lemaire | P. Perez | J. Renardy | A. Roussarie | J. Schuller | B. Vallage | G. Taylor | C. Booth | S. Cartwright | F. Combley | L. Thompson | S. Brandt | G. Giannini | D. Ferguson | Ying Gao | O. Hayes | Y. Saadi | I. Scott | W. Orejudos | A. Wäänänen | M. Aleppo | D. Binnie | H. Sander | S. Monteil | E. Tournefier | M. Pearson | V. Ghete | S. Gonzalez | G. Blair | M. Lehto | A. Misiejuk | A. Jachołkowska | M. Frank | S. Bravo | M. Chmeissani | H. Ruiz | J. Lin | E. Merle | S. Xue | G. Boix | T. Greening | M. Swynghedauw | P. Negus | G. Hansper | J. Sommer | I. Giehl | E. Rohne | C. Mannert | J. Ward | K. Affholderbach | A. Ngac | G. Prange | U. Sieler | S. Armstrong | J. Kile | P. Mcnamara | J. H. Wimmersperg-Toeller | B. Jost | S. Werner | A. Trabelsi | P. Dornan | C. Bowdery | X. Huang | L. Zhang | P. Henrard | J. Lefrancois | O. Leroy | G. Cowan | J. Walsh | K. Hüttmann | E. Lan¸con | A. Böohrer | Y. Pan | W. Männer | J.-P. Less | J. Thomson | Y. Xie | Y. Pan | Y. Pan

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