Learning from knockout reactions using a dispersive optical model

TL;DR

This paper applies the dispersive optical model (DOM) to analyze knockout reactions, linking scattering and bound-state data to improve understanding of nuclear structure and reaction mechanisms, especially in neutron-rich nuclei.

Contribution

It introduces a fully-consistent, data-informed DOM approach to describe knockout reactions, connecting spectroscopic factors with high-momentum nucleon content in nuclei.

Findings

DOM successfully describes electron-induced knockout reactions for $^{40}$Ca and $^{48}$Ca.

Discrepancies in proton-induced knockout suggest the need for improved in-medium interactions.

Connecting high-momentum protons with spectroscopic factor quenching enhances nuclear structure insights.

Abstract

We present the empirical dispersive optical model (DOM) as applied to direct nuclear reactions. The DOM links both scattering and bound-state experimental data through a dispersion relation which allows for fully-consistent, data-informed predictions for nuclei where such data exists. In particular, we review investigations of the electron-induced proton knockout reaction from both $^{40}$Ca and $^{48}$Ca in a distorted-wave impulse approximation (DWIA) utilizing the DOM for a fully-consistent description. Viewing these reactions through the lens of the DOM allows us to connect the documented quenching of spectroscopic factors with increased high-momentum proton content in neutron-rich nuclei. A similar DOM-DWIA description of the proton-induced knockout from $^{40}$Ca, however, does not currently fit in the consistent story of its electron-induced counterpart. With the main difference in the proton-induced case being the use of an effective proton-proton interaction, we suggest that a more sophisticated in-medium interaction would lead to consistent results.