Study of triple-gauge-boson couplings ZZZ, ZZγ and Zγγ at LEP

Neutral triple-gauge-boson couplings ZZZ, ZZγ and Zγγ 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^-→Zγ, using data from the final states γff̄, with f=q or ν, from e⁺e^-→ZZ, using data from the four-fermion final states qq̄qq̄, qq̄μ⁺μ^-, qq̄e⁺e^-, qq̄νν̄, μ⁺μ^-νν̄ and e⁺e^-νν̄, and from e⁺e^-→Zγ^*, in which the final state γ is off mass-shell, using data from the four-fermion final states qq̄e⁺e^- and qq̄μ⁺μ^-. No evidence for the presence of such couplings is observed, in agreement with the predictions of the Standard Model.