We report on the measurement of the leptonic and hadronic cross sections and leptonic forward-backward asymmetries at the Z peak with the L3 detector at LEP. The total luminosity of 40.8 pb-1 collected in the years 1990, 1991 and 1992 corresponds to 1.09 . 10(6) hadronic and 0.98 . 10(5) leptonic Z decays observed. These data allow us to determine the electroweak parameters. From the cross sections we derive the properties of the Z boson: M(Z) = 91 195 +/- 9 MeV GAMMA(Z) = 2494 +/- 10 MeV GAMMA(had) = 1748 +/- 10 MeV GAMMA(l) = 83.49 +/- 0.46 MeV, assuming lepton universality. We obtain an invisible width of GAMMA(inv) = 496.5 +/- 7.9 MeV which, in the Standard Model, corresponds to a number of light neutrino species of N(v) = 2.981 +/- 0.050.
MEASUREMENT OF CROSS-SECTIONS AND LEPTONIC FORWARD-BACKWARD ASYMMETRIES AT THE Z-POLE AND DETERMINATION OF ELECTROWEAK PARAMETERS
SANTOCCHIA, Attilio
1994
Abstract
We report on the measurement of the leptonic and hadronic cross sections and leptonic forward-backward asymmetries at the Z peak with the L3 detector at LEP. The total luminosity of 40.8 pb-1 collected in the years 1990, 1991 and 1992 corresponds to 1.09 . 10(6) hadronic and 0.98 . 10(5) leptonic Z decays observed. These data allow us to determine the electroweak parameters. From the cross sections we derive the properties of the Z boson: M(Z) = 91 195 +/- 9 MeV GAMMA(Z) = 2494 +/- 10 MeV GAMMA(had) = 1748 +/- 10 MeV GAMMA(l) = 83.49 +/- 0.46 MeV, assuming lepton universality. We obtain an invisible width of GAMMA(inv) = 496.5 +/- 7.9 MeV which, in the Standard Model, corresponds to a number of light neutrino species of N(v) = 2.981 +/- 0.050.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
