Amplitude Zeros and Rapidity Correlations in $W\gamma$ and $WZ$   Production in Hadronic Collisions
  A comparative study of amplitude zeros in $W\gamma$ and $WZ$ production in hadronic collisions is presented. The Standard Model amplitude for $q_1 \bar q_2 \rightarrow W^\pm Z $ at the Born-level is shown to exhibit an approximate zero located at $\cos\theta = (g^{q_1}_{-} + g^{q_2}_{-}) / (g^{q_1}_{-} - g^{q_2}_{-})$ at high energies, where the $g^{q_i}_{-}$ ($i=1,2$) are the left-handed couplings of the $Z$-boson to quarks and $\theta$ is the center of mass scattering angle of the $W$-boson. This approximate zero is similar to the well-known radiation zero in $W\gamma$ production. Prospects to observe the amplitude zeros using rapidity correlations between the final state particles are explored. 
U. Baur