Four-body forces in nuclear matter

Abstract

The binding energy contributions to nuclear matter from four-body forces have been estimated. The four nucleon potential is written in coordinate space, and two intermediate nucleons are treated as spectators to give an effective two-body potential. Two-body correlations are included between all four nucleons and, following a coordinate transformation, two of the six dimensions for the spectator nucleons can be integrated analytically. Spin-isospin dependence is extracted and the remaining integrations are done numerically to give a one-pion-exchange-potential-like effective potential similar to the three-body force effective potentials of Loiseau, Nogami, and Ross. Binding energy calculations can then be done in the usual manner. As the number of nucleons increases the effect of exchanges of the spectator nucleons must also be considered. When this is taken into account, the over-all contribution to the energy of nuclear matter is approximately 0.1 MeV attraction.NUCLEAR STRUCTURE Many-body forces, calculated binding $E$ of four-body force; includes correlations; effective two-body potentials.