Taming Deeply Virtual Compton Scattering

Abstract

We study recent Deeply Virtual Compton scattering (DVCS) data within a dual parameterization of the Generalized Parton Distributions (GPDs). This parameterization allows to quantify the maximum amount of information, that can be extracted from DVCS data, in a ``quintessence'' function. We present a ``zero step'' model for the latter solely based on the forward quark density, providing a parameter free prediction for the imaginary part of the DVCS amplitude. It is shown that the bulk effect of the $ep\to ep\gamma$ beam helicity asymmetry can be understood within such a model.

Comments: 4 pages, 3 figures, results corrected for factor 2 in amplitude