Deeply Virtual Compton Scattering on Nucleons and Nuclei

In this book we perform evaluation of DVCS on spin-0 nuclei in three different approaches. In the first one we assume that factorisation works and perform evaluation of nuclear GPDs in convolution appro­ximation. Also, we evaluate the shadowing corrections and extend the applicability to the high energy (Small Bjorken x) region. In the second approach we study the Compton amplitudes for nucleon and nuclei in the Generelazied Vector Meson Dominance (GVMD) model. We found that the model can describe the recent HERA (H1, ZEUS) data for the proton for virtualities 4 and 8 GeV^2, although conventionally the model is assumed to work for virtualities up to 2-3 GeV^2. We also made evaluations of shadowing corrections for heavy nuclei. In the third approach we evaluate GPDs and DVCS cross-sections in Color Glass Condensate (CGC) model, which is valid for small Bjorken x. We found that the DVCS cross-sections undergo a qualitative transition to saturation regime in the small-x domain, in agreement with Froissart bound.