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

TL;DR

This paper interprets DVCS measurements at small x_B in terms of generalized parton distributions, analyzing skewness, t-dependence, and radiative corrections, and provides model-dependent insights into nucleon structure and experimental observables.

Contribution

It offers a partonic interpretation of DVCS data at small x_B, including radiative corrections and a dispersion relation fit, advancing understanding of GPDs and nucleon structure.

Findings

Compatibility with a holographic principle beyond leading order

Extraction of GPD H on the cross-over line

Prediction of beam charge-spin asymmetry at COMPASS

Abstract

We give a partonic interpretation for the deeply virtual Compton scattering (DVCS) measurements of the H1 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 chromomagnetic 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(2,1) 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.