Some Applications Of Nonperterbative QCD

It has proven to be a great challenge to extract information on the properties of hadrons from the rather simple Lagrangian of QCD. In this report, We first used the global color symmetry model (GCM) in combination with some instanton liquid results for the quark propagator in the presence of zero modees to calculate mass and decay constants of σ and π meson. It should be noted that there are no any free parameter in our model, the calculated results agree with experimental data quite well. In this spirit, then we deduced the effective quark-quark interaction with confinement terms and the vacuum condensate at the mean field level in the framework of GCM. The calculated vacuum condensates is compatiable with the range obtained by 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.High energy heavy ion collisions have been the subject of much interest recently due to the possibility of producing a quark-gluon plasma(QGP) in such reactions. We used reduced Bethe-salpeter(BS) equation to study the properties of heavy flavor mesons at a finite temperature. Based on the statistical properties of charmonium energy spectrum determined by the reduced BS equation, we proposed a new mechanism of J/ψ suppression. In addition, we adopt a systemitic equal-time approach to derive the scalar confinement potentical with retardation and used the reduced Bethe-Salpeter with this scalar confinement potential and effective one gluon exchange potential to calculate the mass spectrum and decay constant of heavy quark systems including B_c meson. By comparing with the results obtained without retardation, we find the calculated mass of B_c with retardation is generially small than that without retardation.