Isospin dependence of nucleon (PF2)-P-3 superfluidity in asymmetric nuclear matter

We have investigated the isospin dependence of the neutron and proton (PF2)-P-3 superfluidity in isospin-asymmetric nuclear matter within the framework of the Brueckner-Hartree-Fock approach and the BCS theory. We show that the (PF2)-P-3 neutron and proton pairing gaps depend sensitively on isospin asymmetry of asymmetric nuclear matter. As the isospin asymmetry increases, the neutron (PF2)-P-3 superfluidity becomes stronger and the peak value of the neutron (PF2)-P-3 pairing gap increases rapidly. The isospin dependence of the proton (PF2)-P-3 superfluidity is shown to be opposite to the neutron one. The proton (PF2)-P-3 superfluidity becomes weaker at a higher asymmetry and it even vanishes at high enough asymmetries. At high asymmetries, the neutron (PF2)-P-3 superfluidity turns out to be much stronger than the proton one, implying that the neutron (PF2)-P-3 superfluidity is dominated in the highly asymmetric dense interior of neutron stars.

Single particle properties in asymmetric nuclear matter and TBF rearrangement effect

We have developed the formula and the numerical code for calculating the rearrangement contribution to the single particle (s.p.) properties in asymmetric nuclear matter induced by three-body forces within the framework of the Brueckner theory extended to include a microscopic three-body force (TBF). We have investigated systematically the TBF-induced rearrangement effect on the s.p. properties and their isospin-behavior in neutron-rich nuclear medium. It is shown that the TBF induces a repulsive rearrangement contribution to the s.p. potential in nuclear medium. The repulsion of the TBF rearrangement contribution increases rapidly as a function of density and nucleon momentum. It reduces largely the attraction of the BHF s.p. potential and enhances strongly the momentum dependence of the s.p. potential at large densities and high-momenta. The TBF rearrangement effect on symmetry potential is to enhances its repulsion (attraction) on neutrons (protons) in dense asymmetric nuclear matter.

Differential isospin-fractionation in dilute asymmetric nuclear matter

The differential isospin-fractionation (IsoF) during the liquid-gas phase transition in dilute asymmetric nuclear matter is studied as a function of nucleon momentum. Within a self-consistent thermal model it is shown that the neutron/proton ratio of the gas phase becomes smaller than that of the liquid phase for energetic nucleons, although the gas phase is overall more neutron-rich. Clear indications of the differential IsoF consistent with the thermal model predictions are demonstrated within a transport model for heavy-ion reactions. Future comparisons with experimental data will allow us to extract critical information about the momentum dependence of the isovector strong interaction.

Proton and neutron S-1(0) superfluidity in asymmetric nuclear matter

The proton and neutron S-1(0), pairing gaps and their isospin dependence in isospin asymmetric nuclear matter have been studied by the isospin dependent Brueckner-Hartree-Fock approach and the BCS theory. We have focused on investigating and discussing the effect of three-body force. The calculated results indicate that as the isospin asymmetry increases, the density range of the S-1(0) neutron superfluidity is narrowed slightly and the maximum value of the neutron pairing gap increases 9 while the density domain for the proton superfluidity enlarges rapidly and the peak value of the proton gap decreases remarkably. The three-body force turns out to affect only weakly the neutron S-1(0) superfluidity and its isospin dependence, i. e., it leads to a small reduction of the neutron S-1(0) paring gap. However, the three-body force not only reduces largely the strength of the proton S-1(0) gaps at high densities in highly asymmetric nuclear matter but also suppresses strongly the density domain for the proton S-1(0) superfluidity phase.