Higher order forward spin polarizability

TL;DR

This paper develops a theoretical framework using dispersion integrals and experimental data to guide future measurements of the nucleon's four leading spin polarizabilities through polarized Compton scattering.

Contribution

It constructs the forward amplitude for polarized Compton scattering using dispersion integrals and recent experimental data, providing a method to extract spin polarizabilities.

Findings

Dispersion integrals agree with experimental photoabsorption data

Strategy to extract spin polarizabilities is validated

Framework supports future experimental analysis

Abstract

As a guideline for future experiments to extract the four (leading) spin polarizabilities of the nucleon, we have constructed the forward amplitude for polarized Compton scattering by dispersion integrals. These integrals have been saturated by recently measured helicity-dependent photoabsorption cross sections as well as predictions for pion photoproduction multipoles from several phenomenological descriptions and chiral perturbation theory. The comparison of these results corroborates the strategy to extract the spin polarizabilities by fitting them to polarized Compton data and fixing all higher order spin effects by dispersion relations based on pion photoproduction multipoles.