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Improved measurements of electroweak parameters fromZ decays into fermion pairs

Research output: Contribution to journalJournal article


  • ALEPH Collaboration
<mark>Journal publication date</mark>1992
<mark>Journal</mark>Zeitschrift für Physik C Particles and Fields
Issue number1
Number of pages20
Pages (from-to)1-20
<mark>Original language</mark>English


The properties of theZ resonance are measured on the basis of 190 000Z decays into fermion pairs collected with the ALEPH detector at LEP. Assuming lepton universality,Mz=(91.182±0.009exp±0.020L∶P) GeV,ГZ=(2484±17) MeV, σhad0=(41.44±0.36) nb, andГjad/Гℓℓ=21.00±0.20. The corresponding number of light neutrino species is 2.97±0.07. The forward-back-ward asymmetry in leptonic decays is used to determine the ratio of vector to axial-vector coupling constants of leptons:gv2(MZ2)/gA2(MZ2)=0.0072±0.0027. Combining these results with ALEPH results on quark charge andbb ¯ asymmetries, and τ polarization, sin2θW(MZ2). In the contex of the Minimal Standard Model, limits are placed on the top-quark mass.