A Precise Determination of the Number of Families With Light Neutrinos and of the Boson Partial Widths
Dec, 198913 pages
Published in:
- Phys.Lett.B 235 (1990) 399-411
- Published: 1990
Report number:
- CERN-EP/89-169
Experiments:
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Abstract: (Elsevier)
More extensive and precise results are reported on the parameters of Z decay. On the basis of 20 000 Z decays collected with the ALEPH detector at LEP we find M z =91.182±0.026 (exp.) ±0.030 (beam) GeV, Γ z =2.541±0.056 GeV and σ had 0 =41.4±0.8 nb. The partial widths for the hadronic and leptonic channels are Γ had =1804±44 MeV, Γ e + e − =82.1±3.4 MeV, Γ μ + μ − =87.9±6.0 MeV and Γ τ + τ − =86.1±5.6 MeV, in good agreement with the standard model. On the basis of the average leptonic width Γ ℓ + ℓ − =83.9±2.2 MeV, the effective weak mixing angle is found to be sin 2 θ w ( M z )=0.231±0.008. Usin g the partial widths calculated in the standard model, the number of light neutrino families is N ν =3.01±0.15 (exp.)±0.05 (theor.).- electron positron: colliding beams
- electron positron: annihilation
- Z0: electroproduction
- Z0: mass
- Z0: width
- Z0: nonleptonic decay
- Z0: leptonic decay
- Weinberg angle
- neutrino: flavor
- cross section: hadronic
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