Virtual Compton Scattering and Nucleon Generalized Polarizabilities

Abstract

This review gives an update on virtual Compton scattering (VCS) off the nucleon, ${\gamma }^{\ast }N\to N\gamma$, 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.

54 pages, 27 figures. To be published by: Progress in Particle and Nuclear Physics. 2020. Version #2, sent for Edition

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• Dispersive evaluation of the D-term form factor in deeply virtual Compton scattering
• Measurements of Double-Polarized Compton Scattering Asymmetries and Extraction of the Proton Spin Polarizabilities
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• Generalized polarizabilities of the nucleon in baryon chiral perturbation theory
• Beam-helicity asymmetry in photon and pion electroproduction in the Delta(1232) resonance region at Q^2= 0.35 (GeV/c)^2
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Cited by in corpus (10)

• The Present and Future of QCD
• Generalised parton distributions from the off-forward Compton amplitude in lattice QCD
• Measured proton electromagnetic structure deviates from theoretical predictions
• Low energy doubly-virtual Compton scattering from di-lepton electroproduction on a nucleon
• Measurement of the Generalized Polarizabilities of the Proton at Intermediate $Q^2$
• Leading-order QED radiative corrections to timelike Compton scattering on the proton
• Virtual Compton scattering at low energies with a positron beam
• Electromagnetic polarizabilities of the spin-$\frac{1}{2}$ singly heavy baryons in heavy baryon chiral perturbation theory
• Soft-photon radiative corrections to the $e^{-}p\to e^{-}p{l}^{-}{l}^{+}$ process
• The Proton Electromagnetic Generalized Polarizabilities