Ab initio translationally invariant nucleon-nucleus optical potentials

TL;DR

This paper develops a first-principles method combining the symmetry-adapted no-core shell model with Green's functions to accurately predict nucleon-nucleus scattering, addressing longstanding issues with center-of-mass motion.

Contribution

It introduces a novel ab initio approach that accurately models nucleon-nucleus interactions and resolves center-of-mass motion problems in Green's function formalism.

Findings

Reproduces experimental cross sections and phase shifts for neutron scattering on helium-4.

Resolves the center-of-mass motion issue in Green's function calculations.

Enables first-principles predictions for various nuclear reactions.

Abstract

We combine the \textit{ab initio} symmetry-adapted no-core shell model (SA-NCSM) with the single-particle Green's function approach to construct optical potentials rooted in first principles. Specifically, we show that total cross sections and phase shifts for neutron elastic scattering from a $^4$He target with projectile energies between 0.5 and 10 MeV closely reproduce the experiment. In addition, we discuss an important new development that resolves a long-standing issue with spurious center-of-mass motion in the Green's function formalism for many-body approaches. The new development opens the path for first-principle predictions of cross sections for elastic scattering of single-nucleon projectiles, nucleon capture and deuteron breakup reactions, feasible for a broad range of open-shell spherical and deformed nuclei in the SA-NCSM approach.