Measurement of electroweak parameters from Z decays into fermion pairs

D. Decamp, B. Deschizeaux, C. Goy, J. P. Lees, M. N. Minard, R. Alemany, J. M. Crespo, M. Delfino, E. Fernandez, V. Gaitan, Ll Garrido, P. Mato, R. Miquel, Ll M. Mir, S. Orteu, A. Pacheco, J. A. Perlas, E. Tubau, M. G. Catanesi, D. CreanzaM. de Palma, A. Farilla, G. Iaselli, G. Maggi, M. Maggi, S. Natali, S. Nuzzo, M. Quattromini, A. Ranieri, G. Raso, F. Romano, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, G. Zito, Y. Gao, H. Hu, D. Huang, S. Jin, J. Lin, T. Ruan, T. Wang, W. Wu, Y. Xie, D. Xu, R. Xu, J. Zhang, W. Zhao, H. Albrecht, W. B. Atwood, F. Bird, E. Blucher, G. Bonvicini, F. Bossi, J. Bourotte, D. Brown, T. H. Burnett, H. Drevermann, F. Dydak, R. W. Forty, C. Grab, R. Hagelberg, S. Haywood, B. Jost, M. Kasemann, G. Kellner, J. Knobloch, A. Lacourt, I. Lehraus, T. Lohse, D. Lüke, A. Marchioro, M. Martinez, J. May, S. Menary, A. Minten, A. Miotto, J. Nash, P. Palazzi, F. Ranjard, G. Redlinger, A. Roth, J. Rothberg, H. Rotscheidt, W. von Rüden, R. St Denis, D. Schlatter, M. Takashima, M. Talby, H. Taureg, W. Tejessy, H. Wachsmuth, S. Wasserbaech, S. Wheeler, W. Wiedenmann, W. Witzeling, J. Wotschack, Z. Ajaltouni, M. Bardadin-Otwinowska

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We report on the properties of the Z resonance from 62 500 Z decays into fermion pairs collected with the ALEPH detector at LEP, the Large Electron-Positron storage ring at CERN. We find MZ=(91.193±0.016exp±0.030LEP ) GeV, ΓZ=(2497±31) MeV, σhad0=(41.86±0.66)nb, and for the partial widths Γinv=(489±24) MeV, Γhad(1754±27) MeV, Γee=(85.0±1.6)MeV, Γμμ=(80.0±2.5) MeV, and Γττ=(81.3±2.5) MeV, all in good agreement with the Standard Model. Assuming lepton universality and using a lepton sample without distinction of the final state we measure Γu=(84.3±1.3) MeV. The forward-backward asymmetry in leptonic decays is used to determine the vector and axial-vector weak coupling constants of leptors, gv2(MZ2)=(0.12±0.12) ×10-2 and gA2(MZ2)=0.2528±0.004 0. The number of light neutrino species is Nν=2.91±0.13; the electroweak mixing angle is sin2θW(MZ2)=0.2291 ±0.0040. © 1990 Springer-Verlag.
Original languageEnglish
Pages (from-to)365-391
JournalZeitschrift fur Physik C-Particles and Fields
Issue number3
Publication statusPublished - 1 Sep 1990


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