Generalized parton distributions

These lectures give an introduction to the concept of generalized parton distributions, its phenomenological applications and the implications for the understanding of nucleon structure. We start in Section 1 with a review on nucleon structure functions obtained from deep inelastic scattering and their interpretation in the parton model. The inclusion of QCD corrections requires the factorization of short-distance contributions to partonic cross sections from long-distance dynamics encoded in ( conventional) parton distribution functions (PDFs). This framework will be generalized in Section 2. It is argued that the description of a class of exclusive high-energy processes, like for instance deeply virtual Compton scattering (DVCS), involves generalized parton distributions (GPDs) whose theoretical properties will be discussed in some detail. Section 3 is devoted to the phenomenology of GPDs. We discuss some examples for theoretical parameterizations that can be confronted to experimental data. Finally, Section 4 is devoted to the interpretation of GPDs in impact parameter space (nucleon tomography) and the connection to the distribution of orbital momentum of partons in a fast-moving nucleon.