The charged particle multiplicity distribution of hadronic Z decays was measured on the peak of the Z resonance using the ALEPH detector at LEP. Using a model independent unfolding procedure the distribution was found to have a mean <n> = 20.85 +/- 0.24 and a dispersion D = 6.34 +/- 0.12. Comparison with lower energy data supports the KNO scaling hypothesis in the energy range square-root s = 29-91.25 GeV. At square-root s = 91.25 GeV the shape of the multiplicity distribution is well described by a log-normal distribution, as predicted from a cascading model for multi-particle production. The same model also successfully describes the energy dependence of the mean and width of the multiplicity distribution. A next-to-leading order QCD prediction in the frame-work of the modified leading-log approximation and local parton-hadron duality is found to fit the energy dependence of the mean but not the width of the charged multiplicity distribution, indicating that the width of the multiplicity distribution is a sensitive probe for higher order QCD or non-perturbative effects.

Measurement of the charged particle multiplicity distribution in hadronic Z decays / D. Decamp, B. Deschizeaux, C. Goy, J. Lees, M. Minard, R. Alemany, J. Crespo, M. Delfino, E. Fernandez, V. Gaitan, L. Garrido, L. Mir, A. Pacheco, M. Catanesi, D. Creanza, M. 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, W. Atwood, L. Bauerdick, F. Bird, E. Blucher, G. Bonvicini, F. Bossi, J. Boudreau, T. Burnett, H. Drevermann, R. Forty, C. Grab, R. Hagelberg, S. Haywood, J. Hilgart, B. Jost, M. Kasemann, J. Knobloch, A. Lacourt, E. Lancon, I. Lehraus, T. Lohse, A. Lusiani, A. Marchioro, M. Martinez, P. Mato, S. Menary, T. Meyer, A. Minten, A. Miotto, R. Miquel, H. Moser, J. Nash, P. Palazzi, F. Ranjard, G. Redlinger, L. Rolandi, A. Roth, J. Rothberg, H. Rotscheidt, M. Saich, D. Schlatter, M. Schmelling, W. Tejessy, H. Wachsmuth, S. Wasserbaech, W. Wiedenmann, W. Witzeling, J. Wotschack, Z. Ajaltouni, F. Badaud, M. Bardadinotwinowska, A. Bencheikh, R. Elfellous, A. Falvard, P. Gay, C. Guicheney, P. Henrard, J. Jousset, B. Michel, J. Montret, D. Pallin, P. Perret, J. Proriol, F. Prulhiere, G. Stimpfl, J. Hansen, J. Hansen, P. Hansen, R. Mollerud, B. Nilsson, I. Efthymiopoulos, E. Simopoulou, A. Vayaki, J. Badier, A. Blondel, G. Bonneaud, J. Brient, G. Fouque, A. Gamess, J. Harvey, S. Orteu, A. Rosowsky, A. Rouge, M. Rumpf, R. Tanaka, H. Videau, D. Candlin, E. Veitch, L. Moneta, G. Parrini, M. Corden, C. Georgiopoulos, M. Ikeda, J. Lannutti, D. Levinthal, M. Mermikides, L. Sawyer, A. Antonelli, R. Baldini, G. Bencivenni, G. Bologna, P. Campana, G. Capon, F. Cerutti, V. Chiarella, B. Dettorrepiazzoli, G. Felici, P. Laurelli, G. Mannocchi, F. Murtas, G. Murtas, L. Passalacqua, M. Pepealtarelli, P. Picchi, P. Zografou, B. Altoon, O. Boyle, P. Colrain, A. Halley, I. Tenhave, J. Lynch, W. Maitland, W. Morton, C. Raine, J. Scarr, K. Smith, A. Thompson, R. Turnbull, B. Brandl, O. Braun, R. Geiges, C. Geweniger, P. Hanke, V. Hepp, E. Kluge, Y. Maumary, A. Putzer, B. Rensch, A. Stahl, K. Tittel, M. Wunsch, A. Belk, R. Beuselinck, D. Binnie, W. Cameron, M. Cattaneo, P. Dornan, S. Dugeay, A. Greene, J. Hassard, N. Lieske, S. Patton, D. Payne, M. Phillips, J. Sedgbeer, G. Taylor, I. Tomalin, A. Wright, P. Girtler, D. Kuhn, G. Rudolph, C. Bowdery, T. Brodbeck, A. Finch, F. Foster, G. Hughes, N. Keemer, M. Nuttall, A. Patel, B. Rowlingson, T. Sloan, S. Snow, E. Whelan, T. Barczewski, K. Kleinknecht, J. Raab, B. Renk, S. Roehn, H. Sander, H. Schmidt, F. Steeg, S. Walther, B. Wolf, J. Aubert, C. Benchouk, V. Bernard, A. Bonissent, J. Carr, P. Coyle, J. Drinkard, F. Etienne, S. Papalexiou, P. Payre, B. Pietrzyk, Z. Qian, D. Rousseau, P. Schwemling, M. Talby, S. Adlung, H. Becker, W. Blum, D. Brown, P. Cattaneo, G. Cowan, B. Dehning, H. Dietl, F. Dydak, M. Fernandezbosman, T. Hanslkozanecka, A. Jahn, W. Kozanecki, E. Lange, J. Lauber, G. Lutjens, G. Lutz, W. Manner, Y. Pan, R. Richter, J. Schroder, A. Schwarz, R. Settles, U. Stierlin, R. Stdenis, M. Takashima, J. Thomas, G. Wolf, V. Bertin, J. Boucrot, O. Callot, X. Chen, A. Cordier, M. Davier, J. Grivaz, M. Gros, P. Heusse, P. Janot, D. Kim, F. Lediberder, J. Lefrancois, A. Lutz, J. Veillet, I. Videau, Z. Zhang, F. Zomer, D. Abbaneo, S. Amendolia, G. Bagliesi, G. Batignani, L. Bosisio, U. Bottigli, C. Bradaschia, M. Carpinelli, M. Ciocci, R. Dellorso, I. Ferrante, F. Fidecaro, L. Foa, E. Focardi, F. Forti, C. Gatto, A. Giassi, M. Giorgi, F. Ligabue, E. Mannelli, P. Marrocchesi, A. Messineo, F. Palla, G. Sanguinetti, J. Steinberger, R. Tenchini, G. Tonelli, G. Triggiani, C. Vannini, A. Venturi, P. Verdini, J. Walsh, J. Carter, M. Green, P. March, T. Medcalf, I. Quazi, J. Strong, L. West, T. Wildish, D. Botterill, R. Clifft, T. Edgecock, M. Edwards, S. Fisher, T. Jones, P. Norton, D. Salmon, J. Thompson, B. Blochdevaux, P. Colas, E. Locci, S. Loucatos, E. Monnier, P. Perez, J. Perlas, F. Perrier, J. Rander, J. Renardy, A. Roussarie, J. Schuller, J. Schwindling, B. Vallage, J. Ashman, C. Booth, C. Buttar, R. Carney, S. Cartwright, F. Combley, M. Dogru, F. Hatfield, J. Martin, D. Parker, P. Reeves, L. Thompson, E. Barberio, S. Brandt, C. Grupen, H. Meinhard, L. Mirabito, U. Schafer, H. Seywerd, G. Ganis, G. Giannini, B. Gobbo, F. Ragusa, U. Stiegler, L. Bellantoni, D. Cinabro, J. Conway, D. Cowen, Z. Feng, D. Ferguson, Y. Gao, J. Grahl, J. Harton, R. Jared, R. Johnson, B. Leclaire, C. Lishka, Y. Pan, J. Pater, Y. Saadi, V. Sharma, Z. Shi, Y. Tang, A. Walsh, J. Wear, F. Weber, M. Whitney, S. Wu, G. Zobernig. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 273:1/2(1991), pp. 181-192.

Measurement of the charged particle multiplicity distribution in hadronic Z decays

F. Ragusa;
1991

Abstract

The charged particle multiplicity distribution of hadronic Z decays was measured on the peak of the Z resonance using the ALEPH detector at LEP. Using a model independent unfolding procedure the distribution was found to have a mean = 20.85 +/- 0.24 and a dispersion D = 6.34 +/- 0.12. Comparison with lower energy data supports the KNO scaling hypothesis in the energy range square-root s = 29-91.25 GeV. At square-root s = 91.25 GeV the shape of the multiplicity distribution is well described by a log-normal distribution, as predicted from a cascading model for multi-particle production. The same model also successfully describes the energy dependence of the mean and width of the multiplicity distribution. A next-to-leading order QCD prediction in the frame-work of the modified leading-log approximation and local parton-hadron duality is found to fit the energy dependence of the mean but not the width of the charged multiplicity distribution, indicating that the width of the multiplicity distribution is a sensitive probe for higher order QCD or non-perturbative effects.
Settore FIS/01 - Fisica Sperimentale
Settore FIS/04 - Fisica Nucleare e Subnucleare
1991
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/175866
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