Measurement of electroweak parameters from hadronic and leptonic decays of the Z0

Adeva, B. ; Adriani, O. ; Aguilar-Benitez, M. ; Akbari, H. ; Alcaraz, J. ; Aloisio, A. ; Alverson, G. ; Alviggi, M. G. ; An, Q. ; Anderhub, H. ; Ganguli, S. N. ; et. , al (1991) Measurement of electroweak parameters from hadronic and leptonic decays of the Z0 Zeitschrift für Physik C Particles and Fields, 51 (2). pp. 179-203. ISSN 0170-9739

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We have studied the reactions e+e- → hadrons,e + e -, μ+ μ- and τ+ τ-, in the energy range 88.2 √s 94.2GeV. A total luminosity of 5.5 pb-1, corresponding to approximately 115000 hadronic and 10000 leptonic Z 0 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: Mz=91.181±0.010±0.02(LEP)GeV, Γz= 2501±17MeV, Γhad=1742±19MeV, Γt=83.6±0.8MeV. If we do not assume lepton universality, we obtain for the partial decay widths of the Z 0 into e + e - μ+ μ- and τ + τ-: Γe=83.3 ± 1.1MeV, Γμ=84.5 ± 2.0MeV, Γ τ=84.0 ± 2.7MeV. From the measured ratio of the invisible and the leptonic decay widths of the Z 0, we determine the number of light neutrino species to be Nv =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 Z 0. We obtain g-v= -0.046+0.015-0.012 and g-A = -0.500 ± 0.003 . In the framework of the Standard Model, we estimate the top quark mass to bem t =193-69 +52 ±16 (Higgs) GeV, and we derive a value for the weak mixing angle of sin2θW=1-(M W /M Z )2=0.222 ± 0.008, corresponding to an effective weak mixing angle of sin2θ-W= 0.2315 ± 0.0025.

Item Type:Article
Source:Copyright of this article belongs to Springer-Verlag.
ID Code:15042
Deposited On:13 Nov 2010 13:05
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