AMPLITUDE ZEROS IN W+/-Z PRODUCTION

We demonstrate that the standard model amplitude for f1f2BAR --> W+/-Z at the Born level exhibits an approximate zero located at cos theta = (g-f1 + g-f2)/(g-f1 - g-f2) at high energies, where the g-fi (i = 1,2) are the left-handed couplings of the Z boson to fermions and theta 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 M (+/-, -/+) and strong gauge cancellations in the remaining amplitudes. For non-standard WWZ couplings these cancellations no longer occur and the approximate amplitude zero is eliminated.