Search

In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.

In this paper a new phase structure of neutron star matter including nucleons and delta isobars is presented. Particle fractions populated and pion condensations in neutron star matter are investigated in this model, The existence of the pion condensations can postpone the appearance of delta isobars' We found that both the pion condensation and reduce of the ratio of delta isobar to nucleons couplings can soften the corresponding equation of state. The maximum masses and their corresponding radii of neutron stars are calculated, and the obtained values are in observational region.

Promising high strangeness dibaryons are studied by the extended quark delocalization and color screening model. It is shown that besides H particle and di-Omega, there might be other dibaryon candidates worth to be searched experimentally such as NOmega.

The properties of neutron stars are studied in a relativistic mean-field model with SU(2) chiral symmetry spontaneous breaking being considered. The calculation results indicate that the effects of the chiral symmetry spontaneous breaking are not negligible.

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.

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.

In the framework of the extended relativistic mean-field theory with hyperons, the properties of neutron star matter have been investigated. It is, found that at a density of four to five times that of nuclear matter saturation density po, a neutron star will become a hyperon star. This transition is strongly influenced by the coupling constants of hyperons to mesons and a different parameter set. For a given parameter set, a minimum transition baryon density exists when the hyperon coupling ratios satisfy x(H sigma) = x(H omega) = x(H rho) = 0.65 or x(H sigma) = x(H omega) = 0.62,x(H rho) = 0.7.

Based on the quark propagator in the instanton dilute liquid approximation, we have determined the quark condensate ((q) over bar q), the mixed quark gluon condensate g(s)((q) over bar G(mu nu)sigma(mu nu)q) and the four-quark condensate ((q) over bar Gamma q (q) over bar Gamma q) at the mean-field level in the framework of global color symmetry model. The numerical calculation shows that our result is compatible with the range obtained within other nonperturbative approaches. In particular, we have found that even at the mean-field level the naive vacuum saturation approximation is not a good approximation when we consider nonlocal four-quark condensate.

A nonlinear chiral quark model with topological ghost terms is proposed. The couplings among the light-flavor quarks, the Goldstone boson nonet and the topological ghost field are consistently incorporated in the model. The inclusion of the ghost field coupling is demanded by describing correctly the effect of the axial anomaly Some features of the model are discussed.

The properties of thermal protoneutron star matter including hyperons are investigated in the framework of the relativistic mean field theory (RMFT). In protoneuron star matter, with the increase of the temperature, the critical densities of hyperons decrease, the sequence for appearances of hyperons change, the abundances of hyperons as well as neutrinos increase, and the strong interactions between baryons get weaker. Meanwhile, the abundances of isospin multiple states for nucleons, Σ, and Ξ become identical, leading to isospin saturated symmetric matter, respectively. Moreover, if a protoneutron star is born with higher temperature, it is less likely to convert to a black hole.

The mass spectrum and binding radii of heavy-quark bound states are analyzed in terms of the reduced Bethe-Salpeter equation. The critical values of screening masses for and bound states at finite temperature are obtained and compared with the previous results given by nonrelativistic models.

Based on the determined bilocal field in the global color symmetry model, the effective quark-quark interaction is deduced explicitly in this letter. The result shows that, except for the normal one-pi and one-sigma exchange terms, the confinement terms with screening factors can automatically be obtained.

The equations of state of the neutron star matter are calculated in the relativistic mean-field approximation with different hyperon coupling constants. The properties of neutron stars are studied by solving the Oppenheimer-Volkoff equation. It manifests the properties of neutron stars - change explicitly as different hyperon coupling constants are concerned.

In the framework of the relativistic mean field theory, the effects of the δ meson on protoneutron star matter with hyperons at unite temperature are investigated. In thermal protoneutron star matter, the δ field potential increases with density first and then decreases. Fixing the density, the increase of the temperature suppresses the S field potential. With the inclusion of the δ meson, the threshold densities for hyperons become lower and the abundance of trapped neutrinos decreases. The most important effect of the δ meson is to increase the abundance of hyperons in the inner core range of protoneutron stars. With the rise of the temperature, the density range where the δ meson plays an important role is narrowed and the effects of the δ meson are suppressed. Moreover, the protoneutron star mass and radius are nearly not affected by the δ meson.