The transverse momentum distribution of Drell-Yan pairs in perturbation theory

We calculate, in lowest-order perturbation theory, the cumulative transverse momentum cross section for the Drell-Yan process in the regime m²?p_T²?q², keeping both single and double logarithmic terms. We verify that this distribution takes the proposed form of a product of structure functions evaluated at p_T² and the square of the Sudakov form factor S(p_T²/q²), evaluated to subleading order.