Study of Triple-Gauge-Boson Couplings ZZZ, ZZgam and Zgamgam at LEP

Understand

Neutral triple-gauge-boson couplings ZZZ, ZZgam and Zgamgam have been studied with the DELPHI detector using data at energies between 183 and 208 GeV.

• Limits are derived on these couplings from an analysis of the reactions e+e- -> Zgam, using data from the final states gamma f fbar, with f = q or neutrino, from e+e- -> ZZ, using data from the four-fermion final states q qbar q qbar, q qbar mu+ mu-, q qbar e+ e-, q qbar nu nubar, mu+ mu- nu nubar and e+ e- nu nubar, and from e+e- -> Zgam*, in which the final state gamma is off mass-shell, using data from the four-fermion final states q qbar e+ e- and q qbar mu+ mu-.
• No evidence for the presence of such couplings is observed, in agreement with the predictions of the Standard Model.