Virtual Compton Scattering and Nucleon Generalized Polarizabilities

TL;DR

This review summarizes recent advances in virtual Compton scattering off the nucleon, focusing on theoretical formalisms, experimental extraction methods, and new experimental results on proton generalized polarizabilities in the low-energy regime.

Contribution

It provides an updated overview of the theoretical formalism, extraction techniques, and recent experimental progress in studying nucleon generalized polarizabilities via VCS.

Findings

Recent experimental data have improved understanding of proton GPs.

Dispersion relations and low-energy theorem are key tools for GP extraction.

Progress in low-energy VCS enhances knowledge of nucleon structure.

Abstract

This review gives an update on virtual Compton scattering (VCS) off the nucleon, $\gamma^* N \to N \gamma$, in the low-energy regime. We recall the theoretical formalism related to the generalized polarizabilities (GPs) and model predictions for these observables. We present the GP extraction methods that are used in the experiments: the approach based on the low-energy theorem for VCS and the formalism of Dispersion Relations. We then review the experimental results, with a focus on the progress brought by recent experimental data on proton generalized polarizabilities, and we conclude by some perspectives in the field of VCS at low energy.