Study of the e +e -→Zγ process at LEP and limits on triple neutral-gauge-boson couplings

The process e +e -→Zγ where the Z boson decays into hadrons or neutrinos, is studied with data collected with the L3 detector at LEP at centre-of-mass energies from 189 up to 209 GeV. The cross sections are measured and found to be in agreement with the Standard Model predictions. Limits on triple neutral-gauge-boson couplings, forbidden in the Standard Model at tree level, are derived. Limits on the energy scales at which the anomalous couplings could be manifest are set. They range from 0.3 to 2.3 TeV depending on the new physics effect under consideration. © 2004 Published by Elsevier B.V