Study of the e^+e^- --> Z gamma Process at LEP and Limits on Triple Neutral-Gauge-Boson Couplings

摘要

The process e^+e^- --> Z gamma, where the Z boson decays into hadrons orneutrinos, is studied with data collected with the L3 detector at LEP atcentre-of-mass energies from 189 GeV up to 209 GeV. The cross sections aremeasured and found to be in agreement with the Standard Model predictions.Limits on triple neutral-gauge-boson couplings, forbidden in the Standard Modelat tree level, are derived. Limits on the energy scales at which the anomalouscouplings could be manifest are set. They range from 0.3 TeV to 2.3 TeVdepending on the new physics effect under consideration.