We report on measurements of e+e- annihilation into hadrons and lepton pairs. The data have been collected with the L3 detector at LEP at centre-of-mass energies between 130 and 189 GeV. Using a total integrated luminosity of 243.7 pb^-1, 25864 hadronic and 8573 lepton-pair events are selected for the measurement of cross sections and leptonic forward-backward asymmetries. The results are in good agreement with Standard Model predictions.
Measured cross sections for the hadronic events.
Measured cross sections for the muon-pair events.
Measured cross sections for the tau-pair events.
We report on measurements of e + e − annihilation into hadrons and lepton pairs. The data have been taken with the L3 detector at LEP at center-of-mass energies between 161 GeV and 172 GeV. In a data sample corresponding to 21.2 pb −1 of integrated luminosity 2728 hadronic and 868 lepton-pair events are selected. The measured cross sections and leptonic forward-backward asymmetries agree well with the Standard Model predictions.
No description provided.
No description provided.
No description provided.
With data corresponding to 142 pb −1 accumulated at s = 57.8 GeV by the AMY detector at TRISTAN we measure the cross section of the reactions e + e − → μ + μ − and e + e − → τ + τ − and the symmetry in the angular distributions. For the lowest order cross section we obtain σ μμ = 27.54 ± 0.65 ± 0.95 pb and σ ττ = 28.27 ± 0.87 ± 0.69 pb, and for the forward-backward asymmetry, A μμ = 0.303 ± 0.027 ± 0.008 and A ττ = −0.291 ± 0.040 ± 0.019. These measurements agree with the standard model. Assuming e − μ − τ univrsality we extract the vector and axial coupling constants | gν | = 0.00 ± 0.09 and | g A | = 0.476 ± 0.024. A fit of data to composite models places lower bounds (95% confidence level) on the compositeness scale of 2–4 TeV.
Lowest order cross section and forward-backward asymmetry.
Errors are statistical only.
Lowest order cross section and forward-backward asymmetry.
We report on the measurement of the leptonic and hadronic cross sections and leptonic forward-backward asymmetries at theZ peak with the L3 detector at LEP. The total luminosity of 40.8 pb−1 collected
Results from 1990 data. Additional systematic uncertainty of 0.3 pct.
Results from 1991 data. Additional systematic uncertainty of 0.15 pct.
Results from 1992 data. Additional systematic uncertainty of 0.15 pct.
The search for an additional heavy gauge boson Z′ is described. The models considered are based on either a superstring-motivated E 6 or on a left-right symmetry and assume a minimal Higgs sector. Cross sections and asymmetries measured with the L3 detector in the vicinity of the Z resonance during the 1990 and 1991 running periods are used to determine limits on the Z-Z′ gauge boson mixing angle and on the Z′ mass. For Z′ masses above the direct limits, we obtain the following allowed ranges of the mixing angle, θ M at the 95% confidence level: −0.004 ⪕ θ M ⪕ 0.015 for the χ model, −0.003 ⪕ θ M ⪕ 0.020 for the ψ model, −0.029 ⪕ θ M ⪕ 0.010 for the η model, −0.002 ⪕ θ M ⪕ 0.020 for the LR model,
Data taken during 1990.
Data taken during 1991.
Data taken during 1990.
We have measured both the rates and the forward-backward asymmetry of ℓ + ℓ − from Z 0 →ℓ + ℓ − (where ℓ= μ , τ ) with the L3 detector. We obtained Γ ℓℓ =88±4±3 MeV and the vector neutral current coupling constant, g v =0.00±0.07 and the axial vector neutral current coupling constant, g A =−0.515±0.015.
No description provided.
No description provided.
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