The ALEPH detector at LEP is used to study single photon events in e+e- collisions at the Z resonance. In a total data sample of 15.7 pb-1 taken in 1990 and 1991 scanning the resonance, 400 events were recorded where each has a single deposition of more than 1.5 GeV measured in the polar angular region \costheta(gamma)\ < 0.74 of the electromagnetic calorimeter. It is shown that this number of events can be accounted for by known processes. After subtraction of background events, the invisible width of the Z is determined to be 450 +/- 34(stat.) +/- 34(syst.) MeV. Using Z resonance parameters derived by ALEPH, the corresponding number of light neutrino generations is found to be 2.68 +/- 0.20(stat.) +/- 0.20(syst.).

A direct measurement of the invisible width of the Z from single photon counting / Buskulic, D., Debonis, I., Decamp, D., Ghez, P., Goy, C., Lees, J.p., Minard, M.n., Pietrzyk, B., Ariztizabal, F., Comas, P., Crespo, J.m., Delfino, M., Efthymiopoulos, I., Fernandez, E., Fernandezbosman, M., Gaitan, V., Garrido, L., Mattison, T., Pacheco, A., Padilla, C., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 313:3-4(1993), pp. 520-534. [10.1016/0370-2693(93)90027-F]

A direct measurement of the invisible width of the Z from single photon counting

CREANZA, Donato Maria;IASELLI, Giuseppe;MAGGI, Giorgio Pietro;
1993

Abstract

The ALEPH detector at LEP is used to study single photon events in e+e- collisions at the Z resonance. In a total data sample of 15.7 pb-1 taken in 1990 and 1991 scanning the resonance, 400 events were recorded where each has a single deposition of more than 1.5 GeV measured in the polar angular region \costheta(gamma)\ < 0.74 of the electromagnetic calorimeter. It is shown that this number of events can be accounted for by known processes. After subtraction of background events, the invisible width of the Z is determined to be 450 +/- 34(stat.) +/- 34(syst.) MeV. Using Z resonance parameters derived by ALEPH, the corresponding number of light neutrino generations is found to be 2.68 +/- 0.20(stat.) +/- 0.20(syst.).
1993
A direct measurement of the invisible width of the Z from single photon counting / Buskulic, D., Debonis, I., Decamp, D., Ghez, P., Goy, C., Lees, J.p., Minard, M.n., Pietrzyk, B., Ariztizabal, F., Comas, P., Crespo, J.m., Delfino, M., Efthymiopoulos, I., Fernandez, E., Fernandezbosman, M., Gaitan, V., Garrido, L., Mattison, T., Pacheco, A., Padilla, C., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 313:3-4(1993), pp. 520-534. [10.1016/0370-2693(93)90027-F]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/1552
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