Deeply virtual compton scattering in color dipole formalism

Abstract

In this contribution we summarize recent investigations on the deeply virtual Compton Scattering (DVCS) within the color dipole approach. The color dipole cross section is implemented through the phenomenological saturation model. The role played by its QCD evolution and skewedness effects in the DVCS cross section are discussed. The results are compared with the recent H1 and ZEUS Collaborations data. The skewing factor, defined as the ratio of the imaginary parts of the amplitudes Im A(γ * p → γ * p)/Im A(γ * p → γ p) can be extracted from the data using recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We report on this experimental extraction and compare the results to the theoretical predictions for NLO QCD and the color dipole approach.

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

“…In this article we restrict ourselves to DVCS at small x B , which has been measured at DESY on the electron/positron-proton collider HERA experiments H1 and ZEUS [8,9,7,10]. This has been previously studied in the spirit of the aligned-jet model [47], from high-energy/Regge perspective [48][49][50], in color dipole model [51][52][53][54][55], and in collinear factorization approach at leading order (LO) [56][57][58], next-leading order (NLO) [59][60][61], and next-to-next-leading order (NNLO) [62]. As said above, the view on the partonic content of the proton varies with the approach.…”

Deeply virtual Compton scattering via color dipoles: Nonperturbative effects

“…A priori, one cannot say how important this contribution is in a particular process. As a first approximation, one can just ignore the nonperturbative effects, as was done in [19,20,21,22], and evaluate everything perturbatively. While for DIS this approximation is partially justified due to high virtualities Q 2 in both vertices, for DVCS its validity is questionable, since the final photon is real.…”

DVCS via color dipoles: Nonperturbative effects

“…A priori, one cannot say how important this contribution is in a particular process. As a first approximation, one can just ignore the nonperturbative effects, as was done in [19,20,21,22], and evaluate everything perturbatively. While for DIS this approximation is partially justified due to high virtualities Q 2 in both vertices, for DVCS its validity is questionable, since the final photon is real.…”