Factorization of helicity amplitudes and angular correlations for electroweak processes

Reliable information on the gauge coupling between W’s and Z’s can best be obtained from studying angular correlations of electroweak processes. A simple, general method of directly writing down helicity amplitudes for tree diagrams suitable for studying angular correlations is presented. Emphasis is placed on factorization properties of these amplitudes which automatically exhibit the physical energy and angular dependences in explicit form. Illustrative examples, including $e^{+}$ $e^{\mathrm{-}}$→$W^{+}$ $W^{\mathrm{-}}$, are worked out in detail. Applications to angular-correlation studies are outlined.