Nuclear relativistic hartree-fock approximation with effective pions

The effect of an interaction between the σ - and π -meson fields, as well as that of the mixture of pseudoscalar (PS) and pseudovector (PV) couplings for the πN vertex on the shell structure of finite nuclei are analyzed in the framework of different nonlinear nuclearmodels based on the relativistic Hartree-Fock approximation. For the case of a dominant πN PV coupling, it is found that if the σ - π interaction generates an effective pion mass increasing with the nuclear density, the unrealistic effect of pions on the shell structure can be strongly reduced, keeping, roughly, the contribution of pions to the total binding energy. The πN PS coupling increases slightly the spin-orbit splittings and the binding energy of the single-particle levels.