Left-Handed W Bosons at the LHC
  The production of W bosons in association with jets is an important background to new physics at the LHC. Events in which the W carries large transverse momentum and decays leptonically lead to large missing energy and are of particular importance. We show that the left-handed nature of the W coupling, combined with valence quark domination at a pp machine, leads to a large left-handed polarization for both W^+ and W^- bosons at large transverse momenta. The polarization fractions are very stable with respect to QCD corrections. The leptonic decay of the W bosons translates the common left-handed polarization into a strong asymmetry in transverse momentum distributions between positrons and electrons, and between neutrinos and anti-neutrinos (missing transverse energy). Such asymmetries may provide an effective experimental handle on separating W + jets from top quark production, which exhibits very little asymmetry due to C invariance, and from various types of new physics. 
Z. Bern, G. Diana, L.J. Dixon, F. Febres Cordero, D. Forde, T.   Gleisberg, S. Hoeche, H. Ita, D. A. Kosower, D. Maitre and ...
hep-ph hep-th