Proton-Nucleus Elastic Scattering: Comparison between Phenomenological and Microscopic Optical Potentials

TL;DR

This paper compares microscopic optical potentials derived from chiral nucleon-nucleon forces with phenomenological models in describing proton elastic scattering on various nuclei at energies around 200 MeV, assessing their accuracy and predictive power.

Contribution

It demonstrates that N4LO chiral-based microscopic optical potentials can reliably predict elastic scattering observables across multiple isotopes and energies, including future experimental conditions.

Findings

Microscopic potentials match experimental data well for stable and exotic nuclei.

N4LO chiral potentials provide reliable predictions up to 333 MeV.

The approach offers a consistent framework for nuclear scattering analysis.

Abstract

Elastic scattering is a very important process to understand nuclear interactions in finite nuclei. Despite decades of efforts, the goal of reaching a coherent description of this physical process in terms of microscopic forces is still far from being completed. In previous papers (Phys. Rev. C93, 034619 (2016), Phys. Rev. C96, 044001 (2017)) we derived a nonrelativistic theoretical optical potential from nucleon-nucleon chiral potentials at fourth (N3LO) and fifth order (N4LO). We checked convergence patterns and established theoretical error bands. With this work we study the performances of our optical potential in comparison with those of a successful nonrelativistic phenomenological optical potential in the description of elastic proton scattering data on several isotopic chains at energies around and above 200 MeV. We use the same framework and the same approximations of our previous papers, where the nonrelativistic optical potential is derived at the first-order term within the spectator expansion of the multiple scattering theory and adopting the impulse approximation and the optimum factorization approximation. The cross sections and analyzing powers for elastic proton scattering off calcium, nickel, tin, and lead isotopes are presented for several incident proton energies, exploring the range $156 \le E \le 333$ MeV, where experimental data are available. In addition, we provide theoretical predictions for Ni56 at 400 MeV, which is of interest for the future experiments at EXL. Our results indicate that microscopic optical potentials derived from nucleon-nucleon chiral potentials at N4LO can provide reliable predictions for the cross section and the analyzing power both of stable and exotic nuclei, even at energies where the reliability of the chiral expansion starts to be questionable.