VERTEX CORRECTIONS IN THE NUCLEAR SCHWINGER–DYSON FORMALISM

We develop the Nuclear Schwinger–Dyson (NSD) formalism to include the effects of ladder diagrams by modifying the vertex. In this extension, the NSD equation sums up both ring diagrams and ladder diagrams self-consistently. The results are compared with mean field theory, Hartree Fock and bare-vertex NSD calculations. It is shown that the vertex correction is important from the following viewpoints. First, the vertex correction greatly modifies the meson propagators, and we can avoid the ghost-pole from meson propagators in a self-consistent way. Secondly, it gives a large negative correlation-energy compared with the other calculations; as a result, it gives a softer equation of state which is preferable according to the experimental data.