Skewness Dependence of GPD / DVCS, Conformal OPE and AdS/CFT Correspondence II: a holographic model of GPD

TL;DR

This paper develops a holographic model for generalized parton distributions (GPD) in deeply virtual Compton scattering (DVCS) using gravity dual descriptions, addressing skewness dependence issues in existing Pomeron models.

Contribution

It extends the BPST gravity dual Pomeron formalism to accurately incorporate skewness dependence in GPDs within a holographic framework.

Findings

Constructed Reggeon wavefunctions on AdS5 for generalized formalism

Derived DVCS amplitude in conformal OPE/collinear factorization form

Proposed a holographic GPD model fitting dual parametrization framework

Abstract

Traditional idea of Pomeron/Reggeon description for hadron scattering is now being given theoretical foundation in gravity dual descriptions, where Pomeron corresponds to exchange of spin-$j \in 2\mathbb{Z}$ states in the graviton trajectory. Deeply virtual Compton scattering (DVCS) is essentially a 2 to 2 scattering process of a hadron and a photon, and hence one should be able to study non-perturbative aspects (GPD) of this process by the Pomeron/Reggeon process in gravity dual. We find, however, that even one of the most developed formulations of gravity dual Pomeron (Brower--Polchinski--Strassler--Tan (BPST) 2006) is not able to capture skewness dependence of GPD properly. In Part I (arXiv:1212.3322), therefore, we computed Reggeon wavefunctions on AdS$_5$ so that the formalism of BPST can be generalized. In this article, Part II, we use the wavefunctions to determine the DVCS amplitude, bring it to the form of conformal OPE/collinear factorization, and extract a holographic model of GPD, which naturally fits into the framework known as "dual parametrization" or "(conformal) collinear factorization approach".