Polarization interference in exclusive $V+$jets at all orders in $α_s$

Abstract

Using new methods for computing helicity amplitudes with intermediate helicity-polarized gauge bosons, we revisit the transverse-longitudinal polarization interference in the $pp\to V+{\rm jets}$ process for $V=γ^*,Z^{(*)},W^{(*)}$ decaying to massless leptons. At each order of the strong coupling constant $α_s$ and remaining exclusive with respect to jet kinematics, we show that the polarization interference in $γ^*\to\ell^+\ell^-$ vanishes after phase-space integration over the kinematics of $\ell^\pm$, thereby extending well-known results for the inclusive process. Due to parity violation, cancellations are softened for the $W$ and $Z$ bosons. We give a simple formula to account for fiducial cuts. We comment on the implications for multiboson processes, and the applicability of our results to chiral gauge bosons in new physics scenarios and to polarization measurements of weak bosons in heavy ion collisions.