Amplitude zeros inW±Zproduction

We demonstrate that the standard model amplitude for ${\mathit{f}}_1$f${\mathrm{¯}}_2$→${\mathit{W}}^{\pm }$Z at the Born level exhibits an approximate zero located at cosθ=(${\mathit{g}}_{\mathrm{-}1}^{\mathit{f}}$+${\mathit{g}}_{\mathrm{-}2}^{\mathit{f}}$)/(${\mathit{g}}_{\mathrm{-}1}^{\mathit{f}}$-${\mathit{g}}_{\mathrm{-}2}^{\mathit{f}}$) at high energies, where the ${\mathit{g}}_{\mathrm{-}\mathit{i}}^{\mathit{f}}$ (i=1,2) are the left-handed couplings of the Z boson to fermions and θ is the center of mass scattering angle of the W boson. The approximate zero is the combined result of an exact zero in the dominant helicity amplitudes scrM(±,∓) and strong gauge cancellations in the remaning amplitudes. For nonstandard WWZ couplings these cancellations no longer occur and the approximate amplitude zero is eliminated.