2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/189174We calculate the effects of next-to-leading order perturbative QCD as well as of the quark transverse motion and off-shellness on the Drell-Yan process cross section. By studying the s->infinity behaviour of the cross section in these approaches, we find that the effects of quark off-shellness and intrinsic-k_T parametrize those of higher twists. In particular, the off-shellness of partons generates part of the K-factor type corrections to the leading order cross section. Higher twist contributions to the p_T-spectrum of the Drell-Yan pairs are found to be large for presently accessible energies. The evolution of quark off-shellness distribution with the hard scale is also studied.v2: shortened, references added, typos correctedHigh Energy Physics - PhenomenologyNuclear Theorytext