A precision measurement of the number of neutrino species

B. Adeva, O. Adriani, M. Aguilar-Benitez, H. Akbari, J. Alcaraz, A. Aloisio, G. Alverson, M.G. Alviggi, Q. An, H. Anderhub, A.L. Anderson, V.P. Andreev (+462 others)
1990 Physics Letters B  
A precision measurement of the number of neutrino species Adeva, B.; Adriani, O.; Aguilar-Benitez, M.; Akbari, H.; Alcaraz, J.; Aloisio, A.; Alverson, G.; Alviggi, M.G.; Linde, F.L. We have measured the cross section for e +e-~hadrons over the center of mass energy range of the Z ° peak, from 88.22 to 95.03 GeV. We determine the Z ° mass Mz = 91.164 + 0.013 (experiment) + 0.030 (LEP) GeV. Within the framework of the standard model we determine the invisible width,/zm,~slb~ ~ = 0.502 + 0.018
more » ... and the number of light neutrino species, Nv = 3.01 _+ 0.11. We exclude the existence ofa supersymmetric scalar neutrino having a mass less than 31.4 GeV, at the 95% confidence level. We performed a model independent combined fit to the e+e-~hadrons and e+e-~tx+lx-data to determine total width, leptonic width and hadronic width of the Z °.
doi:10.1016/0370-2693(90)91267-f fatcat:di5r3u7nrjcg7kpuummpqrc5im