Determination of the number of light neutrino species

Determination of the number of light neutrino species

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, M z = (91.174±0.070) GeV, the Z width Γ z=(2.68±0.15) GeV, and of the peak hadronic cross-section, σ had...

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Veröffentlicht in:Physics letters. B 1989-11, Vol.231 (4), p.519-529
Hauptverfasser: Miquel, R., Pacheco, A., Perlas, J.A., Catanesi, M.G., de Palma, M., Farilla, A., Mastrogiacomo, A., Nuzzo, S., Raso, G., Romano, F., Selvaggi, G., Zito, G., Wang, T., Xu, D., Xu, R., Zhao, W., Blucher, E., Drevermann, H., Kasemann, M., Knobloch, J., Lüke, D., Miotto, A., Richstein, J., Roth, A., St.Denis, R., Taureg, H., Wotschack, J., Gay, P., Henrard, P., Jousset, J., Montret, J-C., Prat, J., Petersen, G., Bourotte, J., Brient, J.C., Fouque, G., Miné, P., Videau, H., Candlin, D.J., Sawyer, L., Baldini, R., Felici, G., Mannocchi, G., Flavell, A.J., Martin, D.J., Raine, C., Cameron, W., Miller, D.G., Taylor, G., Girtler, P., Bowdery, C., Finch, A.J., Foster, F., Keemer, N.R., Snow, S.W., Barczewski, T., Renk, B., Nacasch, R., Payre, P., Blum, W., Dehning, B., Cowan, G., Dietl, H., Hauff, D., Jahn, A., Lütjens, G., Lutz, G., Richter, R., Settles, R., Thomas, J., Waltermann, G., Callot, O., Lutz, A.-M., Marotte, P., Bradaschia, C., Foà, L., Focardi, E., Forti, F., Mannelli, E.B., Marrocchesi, P.S., Messineo, A., Green, M.G., McKemey, A.K., Strong, J., Botterill, D.R., Edwards, M., Hill, D.L., Harvey, J., Klopfenstein, C., Renardy, J.-F., Brandt, S., Neugebauer, E., Liello, F., Harton, J.L., Jared, R.C., Leclaire, B.W., Pater, J.R., Sharma, V., Wear, J.A., Xue, S.T.
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Sprache:eng
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High Energy Physics - Experiment
Physics
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Zusammenfassung: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, M z = (91.174±0.070) GeV, the Z width Γ z=(2.68±0.15) GeV, and of the peak hadronic cross-section, σ had peak=(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 N v=3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL.
ISSN:0370-2693
1873-2445
DOI:10.1016/0370-2693(89)90704-1