RELATIVITY DAMPS OPEP IN NUCLEAR-MATTER

Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the ground state energy of nuclear matter is studied. In the study th e pion is derivative-coupled. We find that the role of the tensor forc e in the saturation mechanism is substantially reduced compared to its dominant role in a usual nonrelativistic treatment. We show that the damping of derivative-coupled OPEP is actually due to the decrease of M/M with increasing density. We point out that if derivative-coupled OPEP is the preferred form of nuclear effective Lagrangian nonrelativi stic treatment of nuclear matter is in trouble. Lacking the notion of M it cannot replicate the damping. We suggest an examination of the f easibility of using pseudoscalar coupled pi N interaction before reach ing a final conclusion about nonrelativistic treatment of nuclear matt er.