The Nuclear Tensor Interaction In Covariant Energy Density Functional

The relativistic formalism of the nuclear tensor interaction is firstly pre-sented in this work based on the covariant energy density functional (EDF) the-ory associated with the Fock diagrams, i.e. the relativistic Hartree-Fock theory. With this newly obtained relativistic formalism of the nuclear tensor interaction, we researched the self-consistent tensor effects on the ground states of nucle-i and nuclear matter systems. It is found that the nuclear tensor interaction, as an important ingredient of nuclear force, emerges simultaneously with the presence of Fock diagrams in the RHF theory. Without introducing any new free parameters, the tensor force components, which are naturally involved in the meson-nucleon coupling channels, can be extracted and quantified almost completely by the relativistic formalism, and the tensor sum rule is also exactly fulfilled with the limit that the spin partner states j< and j> share the same radial wave function. The results calculated from the RHF theory show that isoscalar channels include more distinct tensor effects than isovector ones. Due to the covariant character, a unified and self-consistent treatment on both the nuclear tensor and spin-orbit interactions is then achieved by relativistic models with the presence of Fock diagrams, i.e., the RHF theory.With the presented relativistic formalism of nuclear tensor force, the stud-ies on the ground state of nuclei exhibit that the tensor effects on the traditional magic structure show the character spin dependence. The tensor force gives minimum contribution in the spin-saturated cases. However, as the extent of spin-unsaturation increases, the tensor effect is gradually enhanced. Combined with the experimental data of spin-orbit splitting, it is found that the calculat-ed spin-orbit splittings agree better with the experimental data with the tensor force components in the Fock diagrams. For Skyrme Hartree-Fock theory, the tensor effects is introduced by adding a zero-range tensor force component, with two tensor strengths factors a and β which need to be adjusted. From the non-relativistic reduction of the relativistic formalism, these two strength factors can be determined. With the careful analysis on the tensor strengths determined by the relativistic model and non-relativistic ones and the common successes achieved by both models, it well demonstrates the reliability of the relativistic fromalism of the nuclear tensor force in describing nuclear structure, excitation and decay modes.In order to reveal the self-consistent tensor effects on the nuclear matter systems, we performed the comparison between two self-consistent calcula-tions:one with the full EDF and the other with an EDF that drops the tensor force components in the Fock diagrams. With these two self-consistent pro-cedures, the tensor force contributions to the EDF can be completely included or excluded, respectively. It is found thatthe saturation mechanism and other bulk properties of nuclear matter are notably influenced by removing the ten-sor force components in the RHF functional. Due to the fact that the tensor EDFs depend on the momentum p essentially, the tensor effects are gradually enhanced with the increasing density. The systematical analyses show the e-quation of states and density-dependent behavior of the symmetry energy are fairly softened by the naturally involved tensor force components in the Fock diagrams. Consequently, more compact neutron stars are calculated from the full EDFs compared with those from an EDF that drops the tensor force com-ponents. Moreover, for the direct Urca (DU) process that cools the neutron star rapidly, the threshold density is raised by the nuclear tensor force.