Generalized Parton Distributions Models Research Articles

Discussion on the recent proton-DVCS results of Jefferson Lab

We present the recent data issued from the Halls A and B of Jefferson Laboratory for the Deep Virtual Compton Scattering Process on the proton. An important set of data for beam spin asymmetries, unpolarized cross sections and differences of polarized cross sections have been obtained. We modestly attempt a first “global” analysis of these three observables at a single <xB>, <Q2> and <−t> kinematic point. We find that it is extremely challenging to describe simultaneously these data in the framework of a few Generalized Parton Distributions models.

Modeling generalized parton distributions to describe deeply virtual Compton scattering data

We present a new model for generalized parton distributions (GPDs), based on the aligned jet model, which successfully describes the deeply virtual Compton scattering (DVCS) data from H1, ZEUS, HERMES and CLAS. We also present an easily implementable and flexible algorithm for their construction. This new model is necessary since the most widely used models for GPDs, which are based on factorized double distributions, cannot, in their current form, describe the DVCS data when employed in a full QCD analysis. We demonstrate explicitly the reason for the shortcoming in the data description. We also highlight several nonperturbative input parameters which could be used to tune the GPDs, and the t dependence, to the DVCS data using a fitting procedure.