A precision measurement of the number of neutrino species

We have measured the cross section for e +e −→hadrons over the center of mass energy range of the Z 0 peak, from 88.22 to 95.03 GeV. We determine the Z 0 mass M z=91.164±0.013 (experiment) ±0.030 (LEP) GeV. Within the framework of the standard model we determine the invisible width, Γ invisible=0.50...

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Veröffentlicht in:	Physics letters. B 1990-10, Vol.249 (2), p.341-352
Hauptverfasser:	Alviggi, M.G., Behrens, J., Berdugo, J., Biland, A., Borgia, B., Burger, J.D., Capell, M., Chaturvedi, U.K., Civinini, C., Degré, A., DiBitonto, D., Diemoz, M., Dolin, R., Eppling, F.J., Fabre, M., Ferguson, T., Foreman, T., Fukushima, M., Gailloud, M., Glaubman, M., Goldfarb, S., Gordeev, A., Grimes, A., Grinnell, C., Hebert, M., Herten, U., Hilgers, K., Hoorani, H., Kirkby, D., Klimentov, A., König, A.C., Krenz, W., Kunin, A., Lanius, K., Lanzano, S., Lebrun, P., Lecoq, P., Leedom, I., Li, X.G., Lökös, S., Longo, E., Lübelsmeyer, K., Luckey, D., Luminari, L., Malhotra, P.K., Mao, Y.F., Maolinbay, M., Massaro, G.G.G., McMahon, T., Merk, M., Metzger, W.J., Mnich, J., Montanet, L., Morganti, S., Nagy, E., Niessen, L., Pevsner, A., Piroué, P.A., Pojidaev, V., Read, K., Rykaczewski, H., Salicio, J.M., Sauvage, G., Schneegans, M., Schulte, R., Schütte, J., Schwering, G., Sciacca, C., Shevchenko, V., Smirnov, N., Sopczak, A., Starosta, R., Stöhr, B., Stone, H., Strauch, K., Summer, R.L., Suter, H., Swain, J.D., Syed, A.A., Timmermans, C., Ulbricht, J., Urbàn, L., Uwer, U., Viertel, G., Von Dardel, G., Wallraff, W., Wang, X.L., Wang, Z.M., Wenaus, T.J., Wenninger, J., White, M., Wilhelm, R., Wittgenstein, F., Wright, D., Xu, Z.Z., Yang, G., Zabounidis, C., Zeng, M., Zhang, D., Zhang, D.H.
Format:	Artikel
Sprache:	eng
Schlagworte:	High Energy Physics - Experiment Physics
Online-Zugang:	Volltext
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Zusammenfassung:	We have measured the cross section for e +e −→hadrons over the center of mass energy range of the Z 0 peak, from 88.22 to 95.03 GeV. We determine the Z 0 mass M z=91.164±0.013 (experiment) ±0.030 (LEP) GeV. Within the framework of the standard model we determine the invisible width, Γ invisible=0.502±0.018 GeV, and the number of light neutrino species, N ν =3.01±0.11. We exclude the existence of a supersymmetric scalar neutrino having a mass less than 31.4 GeV, at the 95% confidence level. We performed a model independent combined fit to the e +e −→hadrons and e +e −→ μ + μ − data to determine total width, leptonic width and hadronic width of the Z 0.
ISSN:	0370-2693 1873-2445
DOI:	10.1016/0370-2693(90)91267-F