Zhao En-Guang

Calculation of four-quark condensate beyond vacuum saturation approximation

Based on a modification of the global color symmetry model, we have calculated the four-quark condensate [: (q) over bar gamma mu lambdaC degrees /2 q(q) over bar gamma mu lambdaC degrees /2 q :] beyond vacuum saturation approximation by including the contribution of pi and sigma masons. The numerical results show that there is a sizeable correction of the four-quark condensate in comparison with its factorized value using the vacuum saturation approximation.

Ground-state properties of C, O, and Ne isotopes in Hartree-Fock-Bogoliubov calculation with Gogny interaction

Ground-state properties of C, O, and Ne isotopes are described in the framework of Hartree–Fock–Bogoliubov theory with density-dependent finite-range Gogny interaction D1S. We include all the contributions to the Hartree–Fock and pairing field arising from Gogny and Coulomb interaction as well as the center of mass correction in the numerical calculations. These ground-state properties of C, O, and Ne isotopes are compared with available experimental results, Hartree–Fock plus BCS, shell model and relativistic Hartree–Bogoliubov calculations. The agreement between experiments and our theoretical results is pretty well. The predicted drip-line is dependent strongly on the model and effective interaction due to their sensitivity to various theoretical details. The calculations predict no evidence for halo structure predicted for C, O, and Ne isotopes in a previous RHB study.

The Mixed Quark-Gluon Condensate from the Global Color Symmetry Model*

The mixed quark-gluon condensate from the global color symmetry model is derived. It is shown that the mixed quark-gluon condensate depends explicitly on the gluon propagator. This interesting feature may be regarded as an additional constraint on the model of gluon propagator. The values of the mixed quark-gluon condensate from some ansatz for the gluon propagator are compared with those determined from QCD sum rules.

Nuclear Chaotic Behavior in a Two-j Shell Coupled with a Rotor Model*

The chaotic properties for six particles interacting by a monopole pairing force in a two-j shell model coupled with a deformed core are studied in the frame of particle-rotor model. The nearest-neighbor distribution of energy levels and spectral rigidity in the two-j shell are compared with those in the single-j case. The results show that the system is more regular in the two-j model than that in the single-j case.

Potential energy surface in Hartree-Fock theory: Adiabatic or configuration-constrained?

Validity of adiabatic assumption is discussed within the constrained Hartree-Fock theory for self-conjugate nucleus Kr-72. It is shown that the adiabatic assumption does not provide a correct description for the nature of nucleus when a, configuration change is involved. The excited Hartree-Fock states and the continuously-connected constrained Hartree-Fock states are given for the first time by applying the configuration dictated constrained Hartree-Fock theory with Gogny force. The importance of self-consistency between the mean-field and the single particle wave functions is emphasized even when a small number of nucleons are involved in the configuration change.

Nonlocal four-quark condensate and vacuum susceptibilities

Based on the quark propagator in the instanton dilute liquid approximation, we have determined the nonlocal four-quark condensate at the mean-field level in the framework of global color symmetry model. By making use of this formula, the vacuum susceptibility (pion susceptibility) was calculated in this paper. The theoretical analysis and numerical calculation show that even at the mean-field level the naive vacuum saturation approximation is not a good approximation when we consider nonlocal four-quark condensate.

The Structure of the Neutron-Rich Nd Isotopes in the IBM*

The spectra and E2 transition properties of Nd146-156 isotopes are studied in the interacting boson model in the light of new experimental data. It is found that Nd146-150 are in the transition from the vibrational limit to the rotational limit. From Nd-152 onward, the isotopes are nearly perfect rotors. Possible deformation saturation is discussed in the interacting boson model.

Small Current Quark Mass Effects on Dressed-Quark Propagator in an Effective Quark-Quark Interaction Model*

A method for obtaining the small current quark mass dependence of the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach the small current quark mass effects on dressed-quark propagator have been studied. A comparison with previous results is given.

Nonperturbative aspects of axial vector vertex

It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model. Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger-Dyson equation in the rainbow approximation, respectively.

QCD sum rule external field approach and vacuum susceptibilities

Based on QCD sum rule three-point and two-point external field formulas respectively, the vector vacuum susceptibilities are calculated at the mean-field level in the framework of the global color symmetry model. It is shown that the above two approaches of determination of the vector vacuum susceptibility may lead to different results. The reason of this contradiction is discussed.