Experimental effects of the off-shell structure in anomalous neutral triple gauge vertices

We discuss differences between on-shell and off-shell treatments in the search for anomalous neutral triple gauge couplings in e⁺e^- collisions. We find that the usual on-shell framework represents an optimal starting point, covering all scenarios in which a reasonable experimental sensitivity is expected. We show that off-shell effects lead to negligible deviations at the experimental level, provided that e⁺e^-→ff̅ γ and e⁺e^-→ff̅ f^′f^′ analyses are performed in regions where Z^*→ff̅ ,f^′f^′ production is dominant. For consistency reasons, we advocate the use of a natural extension of the on-shell definitions, which takes into account the correct off-shell dependences. Contrary to what has been recently suggested in the literature, we find that no SU(2)_L×U(1)_Y constraints among neutral triple gauge couplings can be imposed in a general case.