Abstract
We report on the properties of theZ resonance from 62 500Z decays into fermion pairs collected with the ALEPH detector at LEP, the Large Electron-Positron storage ring at CERN. We findM Z=(91.193±0.016exp±0.030LEP) GeV, Γ Z =(2497±31) MeV, σ 0had =(41.86±0.66)nb, and for the partial widths Γinv=(489±24) MeV, Γhad(1754±27) MeV, Γ ee =(85.0±1.6)MeV, Γ μμ =(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,g 2v (M 2 Z )=(0.12±0.12)×10−2 andg 2A (M 2 Z )=0.2528±0.0040. The number of light neutrino species isN ν=2.91±0.13; the electroweak mixing angle is sin2θW(M 2Z )=0.2291±0.0040.
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D. Decamp et al. (ALEPH Coll.): Phys. Lett. B 231 (1989) 519; ibid Phys. Lett. B234 (1990) 399; ibid Phys. Lett. B235 (1990) 339
G.S. Abrams et al. (MARK II Coll.): Phys. Rev. Lett. 63 (1989) 724; G.S. Abrams et al. (MARK II Coll.): Phys. Rev. Lett. 63 (1989) 2173; B. Adeva et al. (L3 Coll.): Phys. Lett. B231 (1989) 509; M.Z. Akrawy et al. (OPAL Coll.): Phys. Lett. B231 (1989) 530; P. Aarnio et al. (DELPHI Coll.): Phys. Lett. B231 (1989) 539; B. Adeva et al. (L3 Coll.): Phys. Lett. B236 (1990) 109; B. Adeva et al. (L3 Coll.): Phys. Lett. B237 (1990) 136; M.Z. Akrawy et al. (OPAL Coll.): Phys. Lett. B240 (1990) 497; B. Adeva et al. (L3 Coll.): Phys. Lett. B238 (1990) 122; P. Aarnio et al. (DELPHI Coll.): Phys. Lett. B241 (1990) 425; P. Abreu et al. (DELPHI Coll.): Phys. Lett. B241 (1990) 435; M.Z. Akrawy et al. (OPAL Coll.): Analysis ofZ 0 couplings to Charged Leptons, CERN-EP/90-81, 1990
ALEPH — a Detector for Electron-Positron Annihilations at LEP, submitted to Nucl. Instrum. Methods
F.A. Berends, R. Kleiss: Nucl. Phys. B 228 (1983) 737; M. Böhm, A. Denner, W. Hollik: Nucl. Phys. B 304 (1988) 687; F.A. Berends, R. Kleiss, W. Hollik: Nucl. Phys. B 304 (1988) 712; Computer program BABAMC, courtesy of R. Kleiss
The corresponding cross section published in our previous paper [1] was 0.7% larger due to an inadequate hadron vacuum polarization correction and a slightly different acceptance definition
H. Burkhardt et al.: Z. Phys. C — Particles and Fields 43 (1989) 497
D.Y. Bardin et al.: Monte Carlo group in Proceedings of the Workshop on Z Physics at LEP, CERN Report 89-08, 1989, vol. III, 132
D. Decamp et al. (ALEPH Coll.): Phys. Lett. B 234 (1990) 209
M. Bengtsson, T. Sjöstrand: Phys. Lett. B 185 (1987) 435; G. Marchesini, B.R. Webber: Nucl. Phys. B310 (1988) 461
M. Greco: Phys. Lett. B 177 (1986) 97; M. Greco: Nuovo Cimento 11 (1988) 1
M. Caffo, E. Remiddi, F. Semaria: Proceedings of Workshop on Z Physics at LEP, CERN Report 89-08, 1989, vol. I, 171
S. Jadach, Z. Wąs: Comput. Phys. Commun. 36 (1985) 191; Monte Carlo Group in Proceedings of the Workshop on Z Physics at LEP, CERN Report 89-08, 1989, vol. III, 69
A. Borelli et al.: Nucl. Phys. B 333 (1990) 357
F.A. Berends et al.: Z Line Shape group in Proceedings of the Workshop of Z Physics at LEP, CERN Report 89-08, 1989, vol. I, 89
F.A. Berends, G. Burgers, W.L. van Neerven: Nucl. Phys. B 297 (1988) 429; ibid B304 (1988) 921; computer program ZAPP, courtesy of G. Burgers
M. Martinez et al.: Model Independent Fitting to theZ Line Shape, CERN-PPE 90-109, submitted to Z. Phys. C — Particles and Fields
E.A. Kuraev, V.S. Fadin: Sov. J. Nucl. Phys. 41 (1985) 466; G. Altarelli, G. Martinelli: in Physic at LEP, CERN 86-02, 1986, vol. I, 47; O. Nicrosini, L. Trentadue: Phys. Lett. B196 (1987) 551
A. Hofmann: private communication and LEP note to appear
M. Consoli, W. Hollik, F. Jegerlehner: in Proceedings of the Workshop of Z Physics at LEP, CERN Report 89-08, 1989, vol. I, 7
D.C. Kennedy, B.W. Lynn: SLAC Pub 4039, 1986; ibid D.C. Kennedy, B.W. Lynn: Nucl. Phys. B 322 (1989) 1
G. Montagna et al.: Phys. Lett. B 231 (1989) 492; S. Jadach, Z. Wąs: MPI-PAE/PTH 33/89, 34/89 (1989); D. Bardin et al.: Phys. Lett. B206 (1988) 539; computer program ZBIZON, courtesy of D. Bardin et al.
K. Abe et al.: Phys. Rev. Lett. 62 (1989) 1709
J. Dorenbosch et al.: (CHARM Coll.): Z. Phys. C — Particles and Fields 41 (1989) 567
R.C. Allen et al.: Phys. Rev. Lett. 64 (1990) 1330
G. D'Agostini, W. deBoer, G. Grindhammer: Phys. Lett. B 229 (1989) 160
W.J. Marciano, A. Sirlin: Phys. Rev. Lett. 46 (1981) 163
κ has been computed using the program EXPOSTAR; D.C. Kennedy et al.: Nucl. Phys. B 321 (1989) 83
J. Alitti et al.: (UA2 Coll.): Phys. Lett. B 241 (1990) 150
P. Shalbach (CDF Coll.): proceedings of the APS conference, Washington DC, April 90
H. Abramowicz et al. (CDHS Coll.): Phys. Rev. Lett. 57 (1986) 298; A. Blondel et al.: Z. Phys. C — Particles and Fields 45 (1990) 361; J.V. Allaby et al. (CHARM Coll.): Phys. Lett. B177 (1986) 446; Z. Phys. C — Particles and Fields 36 (1987) 611
D. Decamp et al. (ALEPH Coll.): Searches for the Standard Higgs Boson, CERN/PPE 90-101, 1990
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Now at CERN
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 DEAC02-76ER00881
Supported by the US Department of Energy, contract DEFG05-87ER40319
Supported by the NSF, contract PHY-8451274
Supported by the US Department of Energy, contract DEFC0S-85ER250000
Supported by SLOAN fellowship, contract BR 2703
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 Non Directed Research Fund, Korea Res. Found., 1989
On leave of absence from SLAC, Stanford, CA 94309, USA
On leave of absence from University of Washington, Seattle, WA 98195, USA
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ALEPH Collaboration., Decamp, D., Deschizeaux, B. et al. Measurement of electroweak parameters fromZ decays into fermion pairs. Z. Phys. C - Particles and Fields 48, 365–391 (1990). https://doi.org/10.1007/BF01572019
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DOI: https://doi.org/10.1007/BF01572019