We have measured the cross sections for e + e − → e + e − , e + e − → μ + μ − , e + e − → γγ and e + e − → hadrons in an energy scan at center of mass energies between 39.79 and 46.72 GeV in 30 MeV steps. New spinless bosons, whose existence has been postulated as a possible means to explain the anomalously large radiative width of the Z 0 found at the CERN SPS p p collider, are ruled out in the scan region. The data are used to set limits on the couplings to lepton, photon and quark pairs of bosons with masses above 46.72 GeV.
SIG(C=SM) is the Standard Model predicted cross section.
The differential cross section of the reactione+e−→e+e− at a c.m. energy of 34.7 GeV has been measured. The result, together with our previously measurede+e−→α+α− data, are compared with the standard model predictions. We obtain for the weak neutral current couplings the valuesgv2=0.09×0.06,ga2=0.38×0.08. A fit of the Weinberg mixing angle gives the valuegv2=0.09×0.06,ga2=0.038×0.08. The data are also used to set limits on possible deviations from the pointlike structure of leptons. An upper limit for thee+e− coupling to a heavy spin 0 boson is also given.
Fully corrected results for Bhabha scattering.
The differential cross section for Bhabha scattering.
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Hadronic events obtained with the CELLO detector at PETRA are compared with second order QCD predictions using different models for the fragmentation of quarks and gluons into hadrons. We find that the model dependence in the determination of the strong coupling constant persists when going from first to second order QCD calculations.
ASYMMETRY FOR DATA CORRECTED WITH IF MODEL (ALPHA-S=0.12).
ASSYMETRY FOR DATA CORRECTED WITH SF MODEL (ALPHA-S=0.19).
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By combining results from the MARK-J at PETRA on Bhabha scattering, μ + μ - and τ + τ - production with recent world data from neutrino-electron scattering experiments, we determine unique values for the leptonic weak neutral current coupling constants g V and g A in the framework of electroweak models containing a single Z 0 . In contrast to previous analyses, we only use data from purely leptonic interactions, and therefore avoid the inherent uncertainties resulting from the use of hadronic targets. From the MARK-J data alone in the context of the standard SU(2) ⊗ U (1) model of Glashow, Weinberg and Salam, we find sin 2 θ W =0.24±0.11.
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The reactions e+e−→e+e− and e+e−→μ+μ− have been measured at center-of-mass energies 3.0, 3.8, and 4.8 GeV and production angles of 50°<θ<130° over all azimuthal angles. Agreement with quantum electrodynamics is excellent. New limits for cutoff parameters in quantum-electrodynamic-breakdown models are given.
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CONST(NAME=EXP/THEORY) is the experimental numbers divided by the theoretical predictions.
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