One-Loop Corrections of Single Spin Asymmetries at Twist-3 in Drell-Yan   Processes
  We study single spin asymmetries at one-loop accuracy in Drell-Yan processes in which one of the initial hadrons is transversely polarized. The spin-dependent part of differential cross-sections can be factorized with various hadronic matrix elements of twist-2 and twist-3 operators. These operators can be of even- and odd-chirality. In this work, the studied observables of asymmetries are differential cross-sections with different weights. These weights are selected so that the observables are spin-dependent and their virtual corrections are completely determined by quark form factor. In the calculations of one-loop corrections we meet collinear divergences in the contributions involving chirality-odd and chirality-even operators. We find that all of the divergences can be correctly subtracted. Therefore, our results give an explicit example of QCD factorization with twist-3 operators, especially, QCD factorization with chirality-odd twist-3 operators. 
A.P. Chen, J.P. Ma and G.P. Zhang
hep-ph