A global microscopic description of nucleon-nucleus scattering with quantified uncertainties

TL;DR

This paper introduces a microscopic, parameter-free global nucleon-nucleus optical potential with quantified uncertainties, derived from chiral effective field theory, applicable across a wide range of nuclei and energies, and benchmarked against experimental data.

Contribution

It presents the first microscopic global optical potential with uncertainty quantification based on chiral nuclear forces, covering a broad mass and energy range without adjustable parameters.

Findings

Uncertainty bands accurately match experimental data for stable nuclei.

Potential effectively extends to unstable isotopes due to its microscopic nature.

Provides a reliable tool for analyzing nuclear reactions at next-generation facilities.

Abstract

We develop for the first time a microscopic global nucleon-nucleus optical potential with quantified uncertainties suitable for analyzing nuclear reaction experiments at next-generation rare-isotope beam facilities. Within the improved local density approximation and without any adjustable parameters, we begin by computing proton-nucleus and neutron-nucleus optical potentials from a set of five nuclear forces from chiral effective field theory for 1800 target nuclei in the mass range 12 $\leq$ A $\leq$ 242 for energies between 0 MeV $<$ E $\lesssim$ 150 MeV. We then parameterize a global optical potential for each chiral force that depends smoothly on the projectile energy as well as the target nucleus mass number and isospin asymmetry. Uncertainty bands for elastic scattering observables are generated from a full covariance analysis of the parameters entering in the description of our global optical potential and benchmarked against existing experimental data for stable target nuclei. Since our approach is purely microscopic, we anticipate a similar quality of the model for nucleon scattering on unstable isotopes.