SPIN-DEPENDENT DRELL-YAN IN QCD TO O(ALPHA(2)(S)) - (I) - THE NON-SINGLET SECTOR

A study of the order alpha(s)(2) corrections to the Drell-Yan (non-sin glet) differential cross section for incoming states of arbitrary long itudinal helicities is presented. The transverse momentum distribution s, q(T), of the lepton pair are studied and the calculations of Ellis, Martinelli, and Petronzio (EMP) are extended to include polarized ini tial states. We use the <(MS)over bar> scheme and the 't Hooft-Veltman regularization for the helicity projectors. From our results one can obtain the bulk of the totally inclusive NNLO cross section for the pr oduction of a Drell-Yan pair in the non-singlet sector by a simple int egration over the virtual photon momentum. We show that in the <(MS)ov er bar> scheme helicity is not conserved along the quark lines, unless a finite renormalization is done and one adapts the physical (<(MS)ov er bar>(p)) scheme. This aspect of the calculation is similar to the O (alpha(s)(2)) polarized production of single and double photons. Our s pin-averaged unpolarized differential cross sections agree with the EM P calculations. (C) 1998 Elsevier Science B.V.