No Arabic abstract
The improved quark mass density- dependent model, which has been successfully used to describe the properties of both finite nuclei and bulk nuclear matter, is extended to include the strange quark. The parameters of the model are determined by the saturation properties of bulk matter. Then the given parameter set is employed to investigate both the properties of strange hadronic matter and those of $Lambda$ hypernuclei. Bulk strange hadronic matter consisting of nucleons, $Lambda$- hyperons and $Xi$- hyperons is studied under mean-field approximation. Among others, density dependence of the effective baryon mass, saturation properties and stability of the physical system are discussed. For single-$Lambda$ hypernuclei, single particle energies of $Lambda$ hyperon is evaluated. In particular, it is found that the present model produces a small spin-orbit interaction, which is in agreement with the experimental observations. The above results show that the present model can consistently describe the properties of strange hadronic matter, as well as those of single $Lambda$ hypernuclei within an uniform parameterization.
By using the finite temperature quantum field theory, we calculate the finite temperature effective potential and extend the improved quark mass density-dependent model to finite temperature. It is shown that this model can not only describe the saturation properties of nuclear matter, but also explain the quark deconfinement phase transition successfully. The critical temperature is given and the effect of $omega$- meson is addressed.
An improved quark mass density- dependent model with the non-linear scalar sigma field and the $omega$-meson field is presented. We show that the present model can describe saturation properties, the equation of state, the compressibility and the effective nuclear mass of nuclear matter under mean field approximation successfully. The comparison of the present model and the quark-meson coupling model is addressed.
A new improved quark mass density-dependent model including u, d quarks, $sigma$ mesons, $omega$ mesons and $rho$ mesons is presented. Employing this model, the properties of nuclear matter, neutron matter and neutron star are studied. We find that it can describe above properties successfully. The results given by the new improved quark mass density- dependent model and by the quark meson coupling model are compared.
The ambiguities and inconsistencies in previous thermodynamic treatments for the quark mass density-dependent model are addressed. A new treatment is suggested to obtain the self-consistent results. A new independent variable of effective mass is introduced to make the traditional thermodynamic calculation with partial derivative still practicable. The contribution from physical vacuum has been discussed. We find that the properties of strange quark matter given by quark mass density-dependent model are nearly the same as those obtained by MIT bag model after considering the contribution of the physical vacuum.
A density dependent, effective nucleon-nucleon force of the Skyrme type is derived from the quark-meson coupling model -- a self-consistent, relativistic quark level description of nuclear matter. This new formulation requires no assumption that the mean scalar field is small and hence constitutes a significant advance over earlier work. The similarity of the effective interaction to the widely used SkM$^*$ force encourages us to apply it to a wide range of nuclear problems, beginning with the binding energies and charge distributions of doubly magic nuclei. Finding acceptable results in this conventional arena, we apply the same effective interaction, within the Hartree-Fock-Bogoliubov approach, to the properties of nuclei far from stability. The resulting two neutron drip lines and shell quenching are quite satisfactory. Finally, we apply the relativistic formulation to the properties of dense nuclear matter in anticipation of future application to the properties of neutron stars.