Novel phenomenology of parton distributions from the Drell–Yan process

The Drell–Yan massive lepton-pair production in hadronic collisions provides a unique tool complementary to the Deep-Inelastic Scattering for probing the partonic substructures in hadrons. We review key concepts, approximations, and progress for QCD factorization of the Drell–Yan process in terms of collinear or transverse momentum dependent (TMD) parton distribution functions. We present experimental results from recent fixed-target Drell–Yan as well as W and Z boson production at colliders, focusing on the topics of flavor structure of the nucleon sea as well as the extraction of novel Sivers and Boer–Mulders functions via single transverse spin asymmetries and azimuthal lepton angular distribution of the Drell–Yan process. Prospects for future Drell–Yan experiments are also presented.