We investigate the role of the transverse spin dependence in Drell Yan lepton pair production to NLO in QCD at parton level. In our analysis we deal with the large $p_T$ distributions. We give very compact expressions for the virtual $O(\alpha_s^2)$ corrections to the cross section and show that the singularities factorize. The study is performed in the $\bar{ MS}$ scheme in Dimensional Regularization, and with the t'Hooft-Veltman prescription for $\gamma_5$. A discussion of the structure of the real emissions is included, and detailed methods for the study of these contributions are formulated.
Categories: hep-ph