The differential cross sections for lepton pair production in e+e− annihilation at 29 GeV have been measured and found to be in good agreement with the standard model of the electroweak interaction. With the assumption of e−μ−τ universality, the weak neutral-current couplings are determined to be ga2=0.23±0.05 and gv2=0.03±0.04.
Data requested from authors.
Cross-sections and angular distributions for hadronic and lepton pair final states in e+e- collisions at a centre-of-mass energy near 189 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The results are used to measure the energy dependence of the electromagnetic coupling constant alpha_em, and to place limits on new physics as described by four-fermion contact interactions or by the exchange of a new heavy particle such as a sneutrino in supersymmetric theories with R-parity violation. A search for the indirect effects of the gravitational interaction in extra dimensions on the mu+mu- and tau+tau- final states is also presented.
The cross sections for electron -pair production with various angular cuts.
The forward-backward asymmetry in electron-pair production for cos(theta_e) <0.7.
The angular distribution for electron-pair production. The errors include statistical and systematic effects combined.
Hadron production and lepton-pair production in e+e- collisions are studied with data collected with the L3 detector at LEP at centre-of-mass energies sqrt{s}=192-208GeV. Using a total integrated luminosity of 453/pb, 36057 hadronic events and 12863 lepton-pair events are selected. The cross sections for hadron production and lepton-pair production are measured for the full sample and for events where no high-energy initial-state-radiation photon is emitted prior to the collisions. Lepton-pair events are further investigated and forward-backward asymmetries are measured. Finally, the differential cross sections for electron-positron pair-production is determined as a function of the scattering angle. An overall good agreement is found with Standard Model predictions.
Measured E+ E- --> E+ E- cross section for the inclusive data sample.
Measured E+ E- --> E+ E- cross section for the high-energy data sample.
Measured Forward-Backward asymmetry in E+ E- production for the inclusive data sample.
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 electron-pair events. For Bhabha scattering events both the leptons have to be inside 44 to 136 degrees.
Measured cross sections for the electron-pair events. For Bhabha scattering events both the leptons have to be inside 44 to 136 degrees.
Angular distributions for (E+ E-) events for the high energy event sample (ZETA <25 DEGS) Statistical and systematic errors are combined.
The real-to-imaginary ratio of the p p forward elastic scattering amplitude has been measured at the LEAR facility of CERN by the Coulomb-nuclear interference method at seven beam momenta between 181 and 590 MeV/ c . The ratio is positive at 590 MeV/ c , becomes negative below 500 MeV/ c , reaches a minimum at 260 MeV/ c and then crosses zero again at about 230 MeV/ c .
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