We have investigated the effect of tensor correlations on the depletion of the nuclear Fermi sea in symmetric nuclear matter within the framework of the extended Brueckner-Hartree-Fock approach by adopting the AV 18 two-body interaction and a microscopic three-body force.The contributions from various partial wave channels including the isospin-singlet T = 0 channel,the isospin-triplet T = 1 channel and the T = 0 tensor ~3SD_1 channel have been calculated.The T =0 neutron-proton correlations play a dominant role in causing the depletion of nuclear Fermi sea.The T =0 correlation-induced depletion turns out to stem almost completely from the ~3SD_1 tensor channel.The isospin-singlet T = 0 ~3SD_1 tensor correlations are shown to be responsible for most of the depletion,which amounts to more than 70 percent of the total depletion in the density region considered.The three-body force turns out to lead to an enhancement of the depletion at high densities well above the empirical saturation density and its effect increases as a function of density.
The mass-dependent symmetry energy coefficients asym(A) has been extracted by analysing the heavy nuclear mass differences reducing the uncertainties as far as possible in our previous work.Taking advantage of the obtained symmetry energy coefficient asym(A) and the density profiles obtained by switching off the Coulomb interaction in208 Pb,we calculated the slope parameter L0.11 of the symmetry energy at the density of 0.11 fm-3.The calculated L0.11 ranges from 40.5 Me V to 60.3 Me V.The slope parameter L0.11 of the symmetry energy at the density of 0.11 fm-3is also calculated directly with Skyrme interactions for nuclear matter and is found to have a fine linear relation with the neutron skin thickness of208 Pb,which is the difference of the neutron and proton rms radii of the nucleus.With the linear relation the neutron skin thickness Rn pof208 Pb is predicted to be 0.15–0.21 fm.
We have calculated the nucleon effective mass in symmetric nuclear matter within the framework of the Brueckner-Bethe-Goldstone(BBG) theory,which has been extended to include both the contributions from the ground-state correlation effect and the three-body force(TBF) rearrangement effect.The effective mass is predicted by including the ground-state correlation effect and the TBF rearrangement effect,and we discuss the momentum dependence and the density dependence of the effective mass.It is shown that the effect of ground state correlations plays an important role at low densities,while the TBF-induced rearrangement effect becomes predominant at high densities.
We have calculated and compared the three-body force effects on the properties of nuclear matter under the gap and continuous choices for the self-consistent auxiliary potential within the Brueckner-Hartree-Fock approach by adopting the Argonne V18 and the Bonn B two-body potentials plus a microscopic three-body force(TBF).The TBF provides a strong repulsive effect on the equation of state of nuclear matter at high densities for both the gap and continuous choices.The saturation point turns out to be much closer to the empirical value when the continuous choice is adopted.In addition,the dependence of the calculated symmetry energy upon the choice of the self-consistent auxiliary potential is discussed.
The effect of tensor force on the density dependence of nuclear symmetry energy has been investigated within the framework of the Brueckner-Hartree-Fock(BHF) approach. It is shown that the tensor force manifests its effect via the tensor 3 S D1channel. The density dependence of symmetry energy Esym turns out to be determined essentially by the tensor force from the π meson and ρ meson exchanges via the 3 S D1 coupled channel. Increasing the strength of the tensor component due to the ρ-meson exchange tends to enhance the repulsion of the equation of state of symmetric nuclear matter and leads to the reduction of symmetry energy. The present results confirm the dominant role played by the tensor force in determining nuclear symmetry energy and its density dependence within the microscopic BHF framework.
We calculate the neutron-proton(np)pairing gap in the framework of the extend Bruecker-Hartree-Fock(BHF)approach in combination with the BCS theory by considering the self-energy effect,which is calculated up to the third order.The result shows that the self-energy up to the second order reduces the effective energy gap strongly while the renormalization term enhances it significantly.In addition,the effect of the three-body force(3BF)on the np pairing gap is shown to be negligible.To connect with the np pairing in finite nuclei we propose an effective density-dependent zero-range pairing force with the parameters fitting to the calculated energy gap.
We have calculated the proton spectral functions for finite nuclei by the local density approximation where the nuclear structure is calculated from the Skyrme-Hartree-Fock method and the nuclear matter calculation is performed within the framework of the extended Brueckner-Hartree-Fock approach by adopting the AV18 two-body interaction supplemented with a microscopic three-body force[1].
A systematical investigation of nucleon momentum distributions at various densities and isospin asymmetries for nuclear matter are performed within the extended Brueckner-Hartree-Fock(EBHF)approach.The shapes of the normalized momentum distributions varying with k/kF are shown to be practically identical。
We investigate the neutron and proton single particle (s.p.) potentials of asymmetric nuclear matter and their isospin dependence in various spin-isospin ST channels within the framework of the BruecknerHartree-Fock approach. It is shown that in symmetric nuclear matter, the s.p. potentials in both the isospinsinglet T = 0 channel and isospin-triplet T = 1 channel are essentially attractive, and the magnitudes in the two different channels are roughly the same. In neutron-rich nuclear matter, the isospin-splitting of the proton and neutron s.p. potentials turns out to be mainly determined by the isospin-singlet T = 0 channel contribution which becomes more attractive for the proton and more repulsive for the neutron at higher asymmetries.
