Search

Deeply virtual Compton scattering provides information about the structure of nucleon in the framework of generalized parton distributions. During the last 13 years, DVCS was extensively studied at the HERMES experiment through measurement of various cross-section asymmetries. Due to unique experimental conditions, HERMES has collected a wealth of data on scattering polarized electron and positron beams off unpolarized and longitudinally polarized hydrogen and deuterium targets, as well as off transversely polarized hydrogen targets. The variety of measured asymmetries provides sensitivity to real and/or imaginary parts of different combination of Compton form factors, and thus related GPDs. The HERMES recoil detector is used to separate pure DVCS from associated DVCS processes involving resonance production.

The concept of Generalized Parton Distributions promises an understanding of the generation of the charge, spin, and energy-momentum structure of hadrons by quarks and gluons. Forthcoming measurements with unprecedented accuracy at Jefferson Lab and at CERN will challenge our quantitative description of the three-dimensional structure of hadrons. To fully exploit these future measurements, new tools and models are currently being developed. We explain the difficulties of Generalized Parton Distribution modeling, and present some recent progresses. In particular we describe the symmetrypreserving Dyson-Schwinger and Bethe-Salpeter framework. We also discuss various equivalent parameterizations and sketch how to combine them to obtain models satisfying a priori all required theoretical constraints. At last we explain why these developments naturally fit in a versatile software framework, named PARTONS, dedicated to the theory and phenomenology of GPDs.