Description
Transverse momentum department parton distributions (or simply, TMDs) and generalized parton distributions (GPDs) are fundamental quantum correlation functions of quarks and gluons (collectively referred to as partons) of nucleons and nuclei. They encode rich information that can unravel many aspects of the confined quark and gluon structure of nucleons in momentum and coordinate space, respectively, as well as emergent hadronic properties, including the mechanical properties and spin and mass decompositions. In this presentation, we will give a brief overview on the theory and phenomenology of TMDs and GPDs, focusing on fundamental differences in extracting them from physical processes, especially, the inclusive vs. exclusive processes. Since we only measure scattering cross sections of hadrons and leptons, and can’t measure quarks and gluons directly in isolation, we will carefully distinguish the true confined hadron structure and properties from the collision-induced phenomena once the probed hadron is broken.