3-PARTICLE ONE-HOLE MULTIPLE-SCATTERING CONTRIBUTION TO THE NUCLEAR EFFECTIVE INTERACTION IN MASS-18 NUCLEI

Within the systematic framework of the double partition approach, the three-particle one-hole multiple scattering and Q-box formalisms are combined to give the valence-linked and connected energy-independent effective interaction. All low-lying [2p + 3p1h] contributions to the mass-18 effective interaction are evaluated using an essentially exact energy-dependent reaction matrix based on the Reid SC potential. The low-lying one-body field of the core nucleus is treated consistently with the underlying reaction matrix G through particle- and hole-line self-energy insertions. Center-of-mass motion, folded diagrams and starting energy dependence are properly taken into account throughout. The low-lying [2p + 3p1h] correlations are stongly damped by self-energy insertions. By incorporating only the folded diagram contributions with origins in the low-lying space, the net effect of all low-lying [2p + 3p1h] correlations is to give back the bare-Gplus second-order core-polarization spectra which are found to be in respectable agreement with the experimental spectra. However, including the full folded diagram contribution, which has additional contributions from the high-lying space through the energy dependence of G, leads to final spectra which deviate sizably from experiment. The present results are conclusive in the sense that the treatment is essentially exact for low-lying [2p + 3p1h] correlations which originate from the high-lying two-particle correlations through the reaction matrix G. © 1979.