A DIRECT DETERMINATION OF THE NUMBER OF LIGHT NEUTRINO FAMILIES FROM E+E--]NU-NU-BAR-GAMMA AT LEP

Authors :: Adeva, B
Adriani, O
Aguilarbenitez, M
Akbari, H
Alcaraz, J
Aloisio, A
Alverson, G
Alviggi, M
Ambrosi, G
An, Q
Anderhub, H
Anderson, A
Andreev, V
Angelov, T
Antonov, L
Antreasyan, D
Arce, P
Arefiev, A
Atamanchuk, A
Azemoon, T
Aziz, T
Baba, P
Bagnaia, P
Bakken, J
Baksay, L
Publication Year :: 2016
Abstract: The L3 detector at LEP has been used to determine the number of light neutrino families by measuring the cross section of single photon even in e+e- collisions at energies near the Z0 resonance. We have observed 61 single photon candidates with more than 1.5 GeV of deposited energy in the barrel electromagnetic calorimeter, for a total integrated luminosity of 3.0 pb-1. From a likelihood fir to the single photon cross sections, we determin Nν=3.24 ± 0.46 (statistical) ±0.22 (systematic). © 1992.

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