Exploring the nucleon structure through GPDs and TDAs in hard exclusive processes

to be published in the proceedings of the conference "PHOTON 2011, International Conference on the Structure and the Interactions of the Photon ", Spa, Belgium, 22-27 Mai 2011Generalized Parton Distributions (GPDs) offer a new way to access the quark and gluon nucleon structure. We review recent progress in this domain, emphasizing the need to supplement the experimental study of deeply virtual Compton scattering by its crossed version, timelike Compton scattering. We also describe the extension of the GPD concept to three quark operators and the relevance of their nucleon to meson matrix elements, namely the transition distribution amplitudes (TDAs) which factorize in backward meson electroproduction and related processes. We discuss the main properties of the TDAs.