RELATIVISTIC HAMILTONIANS IN MANY-BODY THEORIES

We discuss the description of a many-body nuclear system using Hamilto nians that contain the nucleon relativistic kinetic energy and potenti als with relativistic corrections. Through the Foldy-Wouthuysen transf ormation, the field theoretical problem of interacting nucleons and me sons is mapped to an equivalent one in terms of relativistic potential s, which are then expanded at some order in 1/m(N). The formalism is a pplied to the Hartree problem in nuclear matter, showing how the resul ts of the relativistic mean field theory can be recovered over a wide range of densities.