Microscopic coupled-channels calculations of nucleus-nucleus scattering including chiral three-nucleon-force effects

Abstract

We analyze16 O-16 O and 12 C-12 C scattering with the microscopic coupled-channels method and investigate the coupled-channels and three-nucleon-force (3NF) effects on elastic and inelastic cross sections. In the microscopic coupled-channels calculation, the Melbourne g-matrix interaction modified according to the chiral 3NF effects is used. It is found that the coupled-channels and 3NF effects additively change both the elastic and inelastic cross sections. As a result, the coupled-channels calculation including the 3NF effects significantly improves the agreement between the theoretical results and the experimental data. The incident-energy dependence of the coupled-channels and 3NF effects is also discussed. Introduction. Microscopic description of many-body nuclear reactions is a long standing subject in nuclear physics. Elastic scattering, which is one of the most basic processes, was first understood phenomenologically with the optical model. The model was founded by the multiple scattering theory [1-3] from the microscopic point of view. According to the theory, elastic scattering is described by multistep processes with a nucleon-nucleon effective interaction. So far many types of density-dependent complex interactions (gmatrix interactions) have been proposed as effective interactions based on the Brueckner theory. It is, however, still not easy to reproduce even the elastic scattering data microscopically.

Dispersion relations applied to double-folding potentials from chiral effective field theory

“…e 2πη σ fus (E c.m. ) , (8) where the Sommerfeld parameter is given by η = Z 1 Z 2 e 2 /(4πε 0 v) with v the asymptotic relative velocity between the two nuclei.…”

“…Even though this framework provides more realistic potentials for the nucleon-nucleus interactions than for the nucleus-nucleus case [4], interesting results have been obtained in such a way, e.g., by considering zero-range contact NN interactions [5,6] or using a G-matrix approach, see, e.g., Refs. [7,8] for recent work. For modern nuclear forces, chiral effective field theory (EFT) has become the standard method for developing interactions rooted in the symmetries of quantum chromodynamics (see, e.g., Refs.…”

Microscopic nucleus-nucleus optical potentials from nuclear matter with uncertainty analysis from chiral forces

“…In contrast to nucleon-nucleus optical potentials, less attention has been paid to the development of microscopic nucleus-nucleus optical potentials, with a few notable exceptions that focus on light systems. These works follow the double-folding approach [11] where either a free-space NN interaction [6][7][8] or a g-matrix interaction [9,10] is folded with nuclear density distributions. When a free-space NN interaction is employed, the double folding approach yields a real interaction which must be supplemented by an imaginary term to account for absorption.…”

“…In Refs. [9,10] a double folding approach is carried out using the Melbourne g-matrix interaction modified to approximately account for effects from three-body forces. By utilizing the g-matrix instead of a free-space interaction, in-medium effects are accounted for.…”

“…In Ref. [10] the authors show the importance of including collective excitations in a coupled-channels framework. They achieve substantially better agreement with data in the coupledchannels calculations, however discrepancies still persist at large scattering angles.…”