Microscopic calculations based on chiral two- and three-nucleon forces for proton- and $^{4}$He-nucleus scattering

TL;DR

This paper uses microscopic calculations based on chiral two- and three-nucleon forces to analyze proton and helium-4 nucleus scattering, revealing that three-nucleon forces significantly affect helium-4 scattering but have minimal impact on proton scattering.

Contribution

It introduces a microscopic framework combining chiral forces with the BHF method and folding model, accurately reproducing scattering data without adjustable parameters and highlighting the role of chiral 3NF effects.

Findings

Chiral 3NF effects are small for proton scattering.

Chiral 3NF effects are sizable for helium-4 scattering.

Chiral 3NF makes the folding potential less attractive and more absorptive.

Abstract

We investigate the effects of chiral three-nucleon force (3NF) on proton scattering at 65 MeV and $^{4}$He scattering at 72 MeV/nucleon from heavier targets, using the standard microscopic framework composed of the Brueckner-Hartree-Fock (BHF) method and the $g$-matrix folding model. For nuclear matter, the $g$ matrix is evaluated from chiral two-nucleon force (2NF) of N$^{3}$LO and chiral 3NF of NNLO by using the BHF method. Since the $g$ matrix thus obtained is numerical and nonlocal, an optimum local form is determined from the on-shell and near-on-shell components of $g$ matrix that are important for elastic scattering. For elastic scattering, the optical potentials are calculated by folding the local chiral $g$ matrix with projectile and target densities. This microscopic framework reproduces the experimental data without introducing any adjustable parameter. Chiral-3NF effects are small for proton scattering, but sizable for $^{4}$He scattering at middle angles where the data are available. Chiral 3NF, mainly in the 2$\pi$-exchange diagram, makes the folding potential less attractive and more absorptive for all the scattering.