Chronology of Milestone Events in Particle Physics - ADEVA 1991D
Chronology of Milestone Events in Particle Physics

ADEVA 1991D

L3 collaboration; Adeva, B. et al.
Measurement of Electroweak Parameters from Hadronic and Leptonic Decays of the Zo
Z. Phys. C51 (1991) 179;

Abstracts
We have studied the reactions e+ e- hadrons, e+ e-, + - and + -, in the energy range 88.2 < < 94.2 GeV. A total luminosity of 5.5 pb-1, corresponding to approximately 115000 hadronic and 10000 leptonic Z0 decays, has been recorded with the L3 detector. From a simultaneous fit to all of our measured cross section data, we obtain assuming lepton universality: center tabular rl MZ&= 91.181 0.010 0.02 (LEP) GeV,
Z&= 2501 17 MeV,
had&= 1742 19 MeV,
l&= 83.6 0.8 MeV. tabular center If we do not assume lepton universality, we obtain for the partial decay widths of the Z0 into e+ e-, +- and + -: center tabular rl e&= 83.3 1.1 MeV,
&= 84.5 2.0 MeV,
&= 84.0 2.7 MeV. tabular center From the measured ratio of the invisible and the leptonic decay widths of the Z0, we determine the number of light neutrino species to be N = 3.05 0.10. We include our measurements of the forward-backward asymmetry for the leptonic channels in a fit to determine the vector and axial-vector neutral current coupling constants of charged leptons to the Z0. We obtain tilde gV = -0.046-0.012+0.015 and tilde gA = -0.500 0.003. In the framework of the Standard Model, we estimate the top quark mass to be mt = 193-69+52 16 (Higgs) GeV, and we derive a value for the weak mixing angle of sin2W = 1 - (MW/MZ)2 = 0.222 0.008, corresponding to an effective weak mixing angle of sin2tildeW = 0.2315 0.0025.

Accelerator CERN-LEP Detectors L3

Related references
More (earlier) information appears in
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Reactions
  e+ e 2HADRON(HADRONS)! 88.2-94.2 GeV (Ecm) cs
  e+ e e e+ 88.2-94.2 GeV (Ecm) cs, asym, const
  e+ e + 88.2-94.2 GeV (Ecm) cs, asym, const
  e+ e + 88.2-94.2 GeV (Ecm) cs, asym, const
  e+ e Zo 88.2-94.2 GeV (Ecm)
  Zo e e+
  Zo +
  Zo +
  Zo 2hadron (hadrons)
  Zo X
  Zo

Particles studied
  Zo mass, w, pw
  ex

Record comments
Confirmation of the number of light neutrinos = 3. L3 Collaboration.
    
  New Comments List of Comments

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