Isospin Dependence Of Asymmetric Nuclear Matter In Relativistic Hartree-Fock Theory

The relativistic Hartree-Fock (RHF) theory considers both the direct and exchange terms of nuclear effective interactions, and the Fock term plays the essential role in isospin-dependent properties of nuclear matter. In this thesis, we investigate the effects of the exchange term on the nuclear symmetry energy by energy density functional, and the isospin-split properties of nucleon mean field in RHF theory.In RHF theory, with the decomposition of energy density functional in terms of kinetic energy, isospin-singlet and isospin-triplet potential energies, we study their contributions to the nuclear symmetry energy, respectively, and we find that the exchange term reduces the kinetic part of the symmetry energy and lead to negative values at supranuclear density region. While the exchange term enhances the isospin-triplet potential part of the symmetry energy, and both isospin-singlet and isospin-triplet potential parts of the symmetry energy are important in RHF theory.In RHF theory, since the non-locality the exchange term of self-energy possesses both momentum-dependence and isospin-dependence in asymmetric nuclear matter. With the self-energy decomposition of the symmetry energy in RHF theory, the effects of exchange term of self-energy on symmetry ener-gy are studied. The results indicate that momentum dependence of self-energy has important negative contribution to symmetry energy at high densities. The isospin dependence of the exchange term of self-energy has important contri-butions to the symmetry energy at high densities. By analysing the correlation between symmetry energy and its density slope at saturation, we find that the uncertainty of the density-dependent symmetry energy mainly comes from the second-order asymmetry-dependent contribution to density slope.The energy-dependence of the nuclear symmetry potential and the isospin-split properties of the nuclear effective mass are also investigated in RHF theo-ry. It is revealed that the isoscalar potential in RHF theory has strong momen-tum (energy) dependence at high energy, and the weaker energy-dependence of isovector potential (symmetry potential) which has important contribution to the single-nucleon potential. In RHF theory, the isospin split of non-relativistic effective mass is mainly determined by E-mass which is less than K-mass, this is contrary to the microscopic results. The energy-dependence of mean free path and nucleon-nucleon (NN) cross section in symmetry and asymmetric nuclear matter is calculated by nuclear optical model potential, which formulated by rel-ativistic impulse approximation (RIA) approach combined with scalar density in RHF theory.