Transverse momentum broadening at NLO and QCD evolution of qˆ

Within the framework of a high-twist approach, we show the first complete next-to-leading order calculation of transverse momentum broadening in semi-inclusive deeply inelastic e+A scattering and Drell-Yan dilepton production in p+A collisions. We demonstrate at one-loop level how QCD factorization holds for multiple scattering in a nuclear medium, and the universality of the associated quark-gluon correlation function. Our calculation also identifies a QCD evolution equation for the quark-gluon correlation function, which determines the QCD factorization scale and the energy dependence of the jet transport parameter qˆ.