Abstract
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,M z =(91.182±0.009exp±0.020L∶P) GeV,Г Z =(2484±17) MeV, σ 0had =(41.44±0.36) nb, andГ jad /Г ℓℓ=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:g 2 v (M 2 Z )/g 2 A (M 2 Z )=0.0072±0.0027. Combining these results with ALEPH results on quark charge and\(b\bar b\) asymmetries, and τ polarization, sin2 θ W (M 2 Z ). In the contex of the Minimal Standard Model, limits are placed on the top-quark mass.
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This paper is dedicated to Emilio Picasso for his contributions as LEP Project Leader
Supported by CAICYT, Spain
Supported by the National Science Foundation of China
Supported by the Danish Natural Science Research Council
Supported by the UK Science and Engineering Research Council
Supported by the US Department of Energy, contract DE-AC02-76ER00881
Supported by the US Department of Energy, contract DE-FG05-87ER40319
Supported by the NSF, contract PHY-8451274
Supported by the US Department of Energy, contract DE-FC0S-85ER250000
Supported by SLOAN fellowship, contract BR2703
Supported by the Bundesministerium für Forschung und Technologie, FRG
Supported by the Institut de Recherche Fondamentale du C.E.A.
Supported by Fonds zur Förderung der wissenschaftlichen Forschung, Austria
Supported by the Korean Science and Engineering Foundation and Ministry of Education
Supported by the World Laboratory
Supported by Alexander von Humboldt Fellowship, FRG
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ALEPH Collaboration., Decamp, D., Deschizeaux, B. et al. Improved measurements of electroweak parameters fromZ decays into fermion pairs. Z. Phys. C - Particles and Fields 53, 1–20 (1992). https://doi.org/10.1007/BF01483868
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DOI: https://doi.org/10.1007/BF01483868