POINT-COUPLING AND NONLINEAR WALECKA MODELS CONNECTION

In the context of infinite nuclear matter, the equation of states obtained from the Walecka model turn out to be the same as those constructed from point-coupling models in which the nucleons interact with each other only when they are in contact.¹ Nonlinear point-coupling models have been applied sucessfully to describe infinite nuclear matter and finite nuclei spectra properties.² A theoretical support for this was presented on the basis of naturalness and naive dimensional analysis.³ For the usual linear Walecka model the infinite meson masses limit leads to a point-coupling model. From this, a quite natural question arises, whether the same kind of masses limit taken in a nonlinear Walecka model would provide a point-coupling model. We construct a modified nonlinear Walecka model Lagrangian in which the infinite meson masses limit can be taken exactly and leads to the contact nonlinear model. This modified nonlinear Walecka model includes higher order couplings. Although the modified and the nonlinear Walecka model at a mean field approach lead to distinct equations of state, the physically relevant content of the models are the same.