Medium corrections to nucleon-nucleon interactions

The Beth-Goldstone equations have been solved for both negative and positive energies to specify two-nucleon G matrices fully off the energy shell. Medium correction effects of Pauli blocking and of the auxiliary potential are included in infinite matter systems characterized by Fermi momenta in the range 0.5 fm -1 to 1.8 fm -1 . The Paris interaction is used as the starting potential in most calculations. Medium corrections are shown to be very significant over a large range of energies and densities. On-the-energy-shell values of G matrices vary markedly from those of free two-nucleon (NN) t matrices which have been solved by way of the Lippmann-Schwinger equation. Off the energy shell, however, the free and medium-corrected Kowalski-Noyes f ratios are quite similar suggesting that useful models of medium-corrected G matrices are appropriately scaled free NN t matrices. The choice of auxiliary potential form is also shown to play a decisive role in the negative energy regime, especially when the saturation of nuclear matter is considered.