The cross-section for e+e− → hadrons in the vicinity of the Z boson peak has been measured with the ALEPH detector at the CERN Large Electron Positron collider, LEP. Measurements of the Z mass, Mz = (91.174±0.070) GeV, the Z width Γz=(2.68±0.15) GeV, and of the peak hadronic cross-section, σhadpeak=(29.3±1.2) nb, are presented. With the constraints of the standard electroweak model, the number of light neutrino species is found to be Nv=3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL

Determination of the number of light neutrino species / D. Decamp, B. Deschizeaux, J. Lees, M. Minard, J. Crespo, M. Delfino, E. Fernandez, M. Martinez, R. Miquel, M. Mir, S. Orteu, A. Pacheco, J. Perlas, E. Tubau, M. Catanesi, M. Depalma, A. Farilla, G. Iaselli, G. Maggi, A. Mastrogiacomo, S. Natali, S. Nuzzo, A. Ranieri, G. Raso, F. Romano, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, G. Zito, Y. Chen, D. Huang, J. Lin, T. Ruan, T. Wang, W. Wu, Y. Xie, D. Xu, R. Xu, J. Zhang, W. Zhao, H. Albrecht, F. Bird, E. Blucher, T. Charity, H. Drevermann, L. Garrido, C. Grab, R. Hagelberg, S. Haywood, B. Jost, M. Kasemann, G. Kellner, J. Knobloch, A. Lacourt, I. Lehraus, T. Lohse, D. Luke, A. Marchioro, P. Mato, J. May, V. Mertens, A. Minten, A. Miotto, P. Palazzi, M. Pepealtarelli, F. Ranjard, J. Richstein, A. Roth, J. Rothberg, H. Rotscheidt, W. Vonruden, D. Schlatter, R. Stdenis, M. Takashima, M. Talby, H. Taureg, W. Tejessy, H. Wachsmuth, S. Wheeler, W. Wiedenmann, W. Witzeling, J. Wotschack, Z. Ajaltouni, M. Bardadinotwinowska, A. Falvard, P. Gay, P. Henrard, J. Jousset, B. Michel, J. Montret, D. Pallin, P. Perret, J. Prat, J. Proriol, F. Prulhiere, H. Bertelsen, F. Hansen, J. Hansen, J. Hansen, P. Hansen, A. Lindahl, B. Madsen, R. Mollerud, B. Nilsson, G. Petersen, E. Simopoulou, A. Vayaki, J. Badier, D. Bernard, A. Blondel, G. Bonneaud, J. Bourotte, F. Braems, J. Brient, M. Ciocci, G. Fouque, R. Guirlet, P. Mine, A. Rouge, M. Rumpf, H. Videau, I. Videau, D. Zwierski, D. Candlin, A. Conti, G. Parrini, M. Corden, C. Georgiopoulos, J. Goldman, M. Ikeda, D. Levinthal, J. Lannutti, M. Mermikides, L. Sawyer, A. Antonelli, R. Baldini, G. Bencivenni, G. Bologna, F. Bossi, P. Campana, G. Capon, V. Chiarella, G. Deninno, B. D’Ettorre Piazzoli, G. Felici, P. Laurelli, G. Mannocchi, F. Murtas, G. Murtas, G. Nicoletti, P. Picchi, P. Zografou, B. Altoon, O. Boyle, A. Flavell, A. Halley, I. Tenhave, J. Hearns, I. Hughes, J. Lynch, D. Martin, R. Oneill, C. Raine, J. Scarr, K. Smith, A. Thompson, B. Brandl, O. Braun, R. Geiges, C. Geweniger, P. Hanke, V. Hepp, E. Kluge, Y. Maumary, M. Panter, A. Putzer, B. Rensch, A. Stahl, K. Tittel, M. Wunsch, G. Barber, A. Belk, R. Beuselinck, D. Binnie, W. Cameron, M. Cattaneo, P. Dornan, S. Dugeay, R. Forty, D. Gentry, J. Hassard, D. Miller, D. Price, J. Sedgbeer, I. Tomalin, G. Taylor, P. Girtler, D. Kuhn, G. Rudolph, T. Brodbeck, C. Bowdery, A. Finch, F. Foster, G. Hughes, N. Keemer, M. Nuttall, B. Rowlingson, T. Sloan, S. Snow, T. Barczewski, L. Bauerdick, K. Kleinknecht, D. Pollmann, B. Renk, S. Roehn, H. Sander, M. Schmelling, F. Steeg, J. Albanese, J. Aubert, C. Benchouk, A. Bonissent, F. Etienne, R. Nacasch, P. Payre, B. Pietrzyk, Z. Qian, W. Blum, P. Cattaneo, M. Comin, B. Dehning, G. Cowan, H. Dietl, M. Fernandezbosman, D. Hauff, A. Jahn, E. Lange, G. Lutjens, G. Lutz, W. Manner, H. Moser, Y. Pan, R. Richter, A. Schwarz, R. Settles, U. Stiegler, U. Stierlin, G. Stimpfl, J. Thomas, G. Waltermann, J. Boucrot, O. Callot, A. Cordier, M. Davier, G. Debouard, G. Ganis, J. Grivaz, P. Heusse, P. Janot, V. Journe, D. Kim, J. Lefrancois, D. Lloydowen, A. Lutz, P. Marotte, J. Veillet, S. Amendolia, G. Bagliesi, G. Batignani, L. Bosisio, U. Bottigli, C. Bradaschia, I. Ferrante, F. Fidecaro, L. Foa, E. Focardi, F. Forti, A. Giassi, M. Giorgi, F. Ligabue, A. Lusiani, E. Mannelli, P. Marrocchesi, A. Messineo, F. Palla, G. Sanguinetti, S. Scapellato, J. Steinberger, R. Tenchini, G. Tonelli, G. Triggiani, J. Carter, M. Green, A. Mckemey, P. March, T. Medcalf, M. Saich, J. Strong, R. Thomas, T. Wildish, D. Botterill, R. Clifft, T. Edgecock, M. Edwards, S. Fisher, D. Hill, T. Jones, G. Mcpherson, M. Morrissey, P. Norton, D. Salmon, G. Tappern, J. Thompson, J. Harvey, B. Blochdevaux, P. Colas, C. Klopfenstein, E. Lancon, E. Locci, S. Loucatos, L. Mirabito, E. Monnier, P. Perez, F. Perrier, B. Pignard, J. Rander, J. Renardy, A. Roussarie, J. Schuller, R. Turlay, J. Ashman, C. Booth, F. Combley, M. Dinsdale, J. Martin, D. Parker, L. Thompson, S. Brandt, H. Burkhardt, C. Grupen, H. Meinhard, E. Neugebauer, U. Schafer, H. Seywerd, K. Stupperich, B. Gobbo, F. Liello, E. Milotti, F. Ragusa, L. Rolandi, L. Bellantoni, J. Boudreau, D. Cinabro, J. Conway, D. Cowen, Z. Feng, J. Harton, J. Hilgart, R. Jared, R. Johnson, B. Leclaire, Y. Pan, T. Parker, J. Pater, Y. Saadi, V. Sharma, J. Wear, F. Weber, S. Wu, S. Xue, G. Zobernig. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 231:4(1989), pp. 519-529. [10.1016/0370-2693(89)90704-1]

Determination of the number of light neutrino species

F. Ragusa;
1989

Abstract

The cross-section for e+e− → hadrons in the vicinity of the Z boson peak has been measured with the ALEPH detector at the CERN Large Electron Positron collider, LEP. Measurements of the Z mass, Mz = (91.174±0.070) GeV, the Z width Γz=(2.68±0.15) GeV, and of the peak hadronic cross-section, σhadpeak=(29.3±1.2) nb, are presented. With the constraints of the standard electroweak model, the number of light neutrino species is found to be Nv=3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL
Settore FIS/01 - Fisica Sperimentale
Settore FIS/04 - Fisica Nucleare e Subnucleare
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/175759
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