Dispersion Theory in Electromagnetic Interactions

Abstract

We review various applications of dispersion relations (DRs) to the electromagnetic structure of hadrons. We discuss the way DRs allow one to extract information on hadron structure constants by connecting information from complementary scattering processes. We consider the real and virtual Compton scattering processes off the proton, and summarize recent advances in the DR analysis of experimental data to extract the proton polarizabilities, in comparison with alternative studies based on chiral effective field theories. We discuss a multipole analysis of real Compton scattering data, along with a DR fit of the energy-dependent dynamical polarizabilities. Furthermore, we review new sum rules for the double-virtual Compton scattering process off the proton, which allow for model independent relations between polarizabilities in real and virtual Compton scattering, and moments of nucleon structure functions. The information on the double-virtual Compton scattering is used to predict and constrain the polarizability corrections to muonic hydrogen spectroscopy.

preprint version of a review to appear in Ann. Rev. Nucl. Part. Sci. 68 (2018)

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Cited by in corpus (20)

• The Spin Structure of the Nucleon
• The Present and Future of QCD
• The proton structure in and out of muonic hydrogen
• Forward doubly-virtual Compton scattering off the nucleon in chiral perturbation theory: II. Spin polarizabilities and moments of polarized structure functions
• Dispersive evaluation of the Lamb shift in muonic deuterium from chiral effective field theory
• Proton scalar dipole polarizabilities from real Compton scattering data, using fixed-t subtracted dispersion relations and the bootstrap method
• First extraction of the scalar proton dynamical polarizabilities from real Compton scattering data
• Measured proton electromagnetic structure deviates from theoretical predictions
• Forward doubly-virtual Compton scattering off the nucleon in chiral perturbation theory: the subtraction function and moments of unpolarized structure functions
• Virtual Compton Scattering and Nucleon Generalized Polarizabilities
• Virtual Compton Scattering measurements in the nucleon resonance region
• Compton Scattering off Pions and Electromagnetic Polarizabilities
• The subtraction contribution to the muonic-hydrogen Lamb shift: a point for lattice QCD calculations of the polarizability effect
• Low energy doubly-virtual Compton scattering from di-lepton electroproduction on a nucleon
• A new Monte Carlo-based fitting method
• Lepton mass effects for beam-normal single-spin asymmetry in elastic muon-proton scattering
• Virtual Compton scattering at low energies with a positron beam
• Soft-photon radiative corrections to the $e^{-}p\to e^{-}p{l}^{-}{l}^{+}$ process
• The Proton Electromagnetic Generalized Polarizabilities
• Energy of a point-like neutron in an external electromagnetic field