Nuclear matter calculation with and without isobars, by the matrix inversion method and comparison of nuclear matter G-matrix with the free scattering matrix

Matrix inversion in momentum space is a powerful method for solving the Lippmann-Schwinger equation in two nucleon scattering and the Bethe-Goldstone equation in nuclear matter. It is seen that the method can also be applied to potentials having no analytic form in momentum space. For this the super soft core potential of de Tourreil, Rouben and Sprung which has a step function line core of about 200 MeV and a complicated structure is used. Recently the effect of the isobar Δ(1236) resonance on the binding and saturation of nuclear matter has been investigated by Green and Niskanen and others for the Reid soft core potentials. It is noted that the matrix inversion with numerical integration in co-ordinate space also works for the Reid potential when the effect of Δ(1236) is explicitly included into the calculations. (auth.)