Covariant density functional theory for nuclear matter

The EOS of nuclear matter is studied in the framework of relativistic density dependent hadron field theory (DDRH) and results are compared to the results of the phenomenological density dependent approach DD-ME1 which is devised to fit the properties of the symmetric nuclear matter around the normal nuclear matter density . Nuclear interactions were described by a covariant density functional theory using baryons and mesons. In this work medium dependent modifications of the nuclear interactions are taken into account with density dependent meson-baryon vertices with momentum corrections. We showed that Lorentz invariance of the Lagrangian, the covariance of the field equations and thermodynamical consistency require a formulation in terms of vertex functionals depending themselves on the field operators. The relation of the DDRH vertex functionals to DB in-medium interactions are discussed. Using relativistic mean-field approximation in DDRH, we have calculated the following properties of symmetric and asymmetric nuclear matter and pure neutron matter: energy density, pressure, binding energy, symmetry energy, effective nucleon mass, compressibility and speed of sound in nuclear medium as functions of the density and of the nuclear asymmetry parameter