Generalized parton distributions: Status and perspectives

TL;DR

This paper reviews recent advances in generalized parton distributions (GPDs), highlighting their theoretical foundations, applications in high-Q2 processes, and their role in understanding nucleon structure through various experimental and modeling approaches.

Contribution

It provides a comprehensive overview of new theoretical methods, phenomenological insights, and the significance of GPDs in small-x physics and nucleon imaging.

Findings

Development of t-channel GPD parametrizations and dispersion relations

Experimental validation of small-size configuration dominance in meson production

Application of GPDs to small-x physics and diffraction phenomena

Abstract

We summarize recent developments in understanding the concept of generalized parton distributions (GPDs), its relation to nucleon structure, and its application to high-Q2 electroproduction processes. Following a brief review of QCD factorization and transverse nucleon structure, we discuss (a) new theoretical methods for the analysis of deeply-virtual Compton scattering (t-channel-based GPD parametrizations, dispersion relations); (b) the phenomenology of hard exclusive meson production (experimental tests of dominance of small-size configurations, model-independent comparative studies); (c) the role of GPDs in small-x physics and pp scattering (QCD dipole model, central exclusive diffraction). We emphasize the usefulness of the transverse spatial (or impact parameter) representation for both understanding the reaction mechanism in hard exclusive processes and visualizing the physical content of the GPDs.