Ab initio folding potentials for nucleon-nucleus scattering based on no-core shell-model one-body densities

Abstract

Background: Calculating microscopic optical potentials for elastic nucleon-nucleus scattering has already led to large body of work in the past. For folding first-order calculations the nucleon-nucleon (NN) interaction and the one-body density of the nucleus were taken as input to rigorous calculations in a spectator expansion of the multiple scattering series.Purpose: Based on the Watson expansion of the multiple scattering series we employ a nonlocal translationally invariant nuclear density derived from a chiral next-to-next-to-leading order (NNLO) and the very same interaction for consistent full-folding calculation of the effective (optical) potential for nucleon-nucleus scattering for light nuclei.Methods: The first order effective (optical) folding potential is computed by integrating over the nonlocal, translationally invariant NCSM one-body density and the off-shell Wolfenstein amplitudes A and C. The resulting nonlocal potential serves as input for a momentum-space Lippmann-Schwinger equation, whose solutions are summed to obtain the nucleon-nucleus scattering observables. Results:We calculate scattering observables, such as total, reaction, and differential cross sections as well as the analyzing power and the spin-rotation parameter, for elastic scattering of protons and neutrons from 4 He, 6 He, 12 C, and 16 O, in the energy regime between 100 and 200 MeV projectile kinetic energy, and compare to available data.Conclusions: Our calculations show that the effective nucleon-nucleus potential obtained from the first-order term in the spectator expansion of the multiple scattering expansion describes experiments very well to about 60 degrees in the center-of-mass frame, which coincides roughly with the validity of the NNLO chiral interaction used to calculate both the NN amplitudes and the one-body nuclear density.

A Guided Tour of ab initio Nuclear Many-Body Theory

“…Optical potentials can also be constructed by folding scattering T-matrices with ab initio density matrices. This technique was applied for NCSM density matrices by two collaborations in references [332,333] and [334,335], respectively, and more applications are underway.…”

Nuclear Dynamics and Reactions in the Ab Initio Symmetry-Adapted Framework

“…A series of studies constructed the leading-order ab initio effective nucleon-nucleus potential, which is nonlocal and energy dependent (48,49,148). This potential has been used to calculate reaction observables, such as cross sections and analyzing power A y , in helium isotopes and other light nuclei, including 12 C and 16 O.…”

Ab Initio Optical Potentials and Nucleon Scattering on Medium Mass Nuclei

“…The nuclear structure method was applied recently obtaining good reproduction of 40 Ca scattering based on the Gogny D1S interaction [11]. Other approaches, based on the nucleonnucleon T-matrix and folding with the nuclear density have proven to be effective [12][13][14][15].…”