Importance of high-lying intermediate excitations on the nuclear effective interaction

Abstract
A particular third-order diagram which contributes to the effective two-body interaction in mass-18 nuclei is computed up to intermediate excitations of 26ω. We find that our results have not converged by 26ω and that the slow decrease in the higher-lying contributions is mainly due to the strong short-range repulsion in the central components of the nucleon-nucleon force.