Deeply virtual Compton scattering at small xB and the access to the GPD H

We give a partonic interpretation for the deeply virtual Compton scattering (DVCS) measurements of the HI and ZEUS Collaborations in the small-x(B) region in terms of generalized parton distributions. Thereby we have a closer look at the skewness effect, parameterization of the t-dependence, revealing the chromo-magnetic pomeron, and at a model-dependent access to the anomalous gravitomagnetic moment of nucleon. We also quantify the reparameterization of generalized parton distributions resulting from the inclusion of radiative corrections up to next-to-next-to-leading order. Beyond the leading order approximation, our findings are compatible with a 'holographic' principle that would arise from a (broken) SO(2, I) symmetry. Utilizing our leading-order findings, we also perform a first model-dependent dispersion relation fit of HERMES and JLAB DVCS measurements. From that we extract the generalized parton distribution H on its cross-over line and predict the beam charge-spin asymmetry, measurable at COMPASS. (C) 2010 Elsevier B.V. All rights reserved.