W bosons produced at high transverse momentum in hadron collisions can
have polarization along the direction perpendicular to the production
plane, which is odd under naive-T-reversal where both the
three-momenta and angular momenta are reversed. Perturbative QCD
predicts non-zero polarization at the one-loop level, which can be
measured as parity-odd components in the angular distribution of
charged leptons from the decay of W bosons. We perform a
detector-level simulation with the generator aMC@NLO, and demonstrate
that the asymmetry can be observed at the 8 TeV LHC with 20 fb^-1 of
data. If confirmed, it will be the first experimental measurement of
the sign of the imaginary part of one-loop QCD amplitudes.