Elsevier

Physics Letters B

Volume 275, Issues 1–2, 23 January 1992, Pages 209-221
Physics Letters B

A direct determination of the number of light neutrino families from e+e→ννγ at LEP

https://doi.org/10.1016/0370-2693(92)90877-7Get rights and content

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).

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    Supported by the German Bundesministerium für Forschung und Technologie.

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