Extracting Neutron Polarizabilities from Compton Scattering on The Quasi-Free Neutrons in $\gamma \text{d}\rightarrow\gamma \text{n p}$

TL;DR

This paper uses chiral effective field theory to analyze Compton scattering on quasi-free neutrons in deuterium, aiming to extract neutron electric and magnetic polarizabilities from experimental data.

Contribution

It provides a novel theoretical framework for extracting neutron polarizabilities from inelastic Compton scattering data using chiral EFT in the quasi-free neutron kinematic region.

Findings

Triple differential cross-sections computed for 200-400 MeV photon energies.

Impulse approximation dominates the scattering process.

Small corrections from final state interactions and meson exchange currents.

Abstract

Compton scattering processes are ideal to study electric and magnetic dipole polarizabilities of nucleons. These fundamental quantities parametrize the responses of the internal degrees of freedoms to a monochromatic photon probe. In this work, the inelastic channel $\gamma d\rightarrow \gamma np$ is treated in $\chi$EFT, with a focus on the kinematic region of the neutron quasi-free peak, where the momentum of the outgoing proton is small enough that it is considered to remain at rest. This provides access to the Compton scattering process $\gamma n \rightarrow \gamma n$, from which the scalar polarizabilites of the neutron, $\alpha_{E1}$ and $\beta_{M1}$, are extracted. Using $\chi$EFT, triple differential cross-sections $d^3\sigma/dE_nd\Omega_{\gamma'} \Omega_n$ in the photon energy range of 200-to-400 MeV are computed. The biggest contribution comes from the impulse approximation, with small corrections stemming from final state interactions, meson exchange currents and rescattering. In this presentation, we report progress and preliminary results.