Determination of the number of light neutrino species

, ALEPH Collaboration (1989) Determination of the number of light neutrino species. Physics Letters B, 231 (4). pp. 519-529. ISSN 0370-2693

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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, Mz = (91.174±0.070) GeV, the Z width Γz=(2.68±0.15) GeV, and of the peak hadronic cross-section, σhadpeak=(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 Nv=3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL.

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Journal Article
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Physics Letters B
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03 May 2013 04:25
Last Modified:
21 Nov 2022 23:38