Amplitude Zeros in $W^\pm Z$ Production

Paper

Abstract

We demonstrate that the Standard Model amplitude for

at the Born-level exhibits an approximate zero located at

at high energies, where the

(

) are the left-handed couplings of the

-boson to fermions and

is the center of mass scattering angle of the

-boson. The approximate zero is the combined result of an exact zero in the dominant helicity amplitudes

and strong gauge cancelations in the remaining amplitudes. For non-standard

couplings these cancelations no longer occur and the approximate amplitude zero is eliminated.