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.).

D., B., I., D., D., D., P., G., C., G., J. P., L., et al. (1993). A Direct Measurement of the Invisible Width of the Z From Single photon Counting. PHYSICS LETTERS. SECTION B, 313(3-4), 520-534 [10.1016/0370-2693(93)90027-F].

A Direct Measurement of the Invisible Width of the Z From Single photon Counting

BOTTIGLI, UBALDO;CIOCCI, MARIA AGNESE;MARROCCHESI, PIER SIMONE;
1993-01-01

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
D., B., I., D., D., D., P., G., C., G., J. P., L., et al. (1993). A Direct Measurement of the Invisible Width of the Z From Single photon Counting. PHYSICS LETTERS. SECTION B, 313(3-4), 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/11365/36269
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