Heavy Mesons And Baryons In A Chiral Quark Model

Quantum Chromodynamics (QCD) is believed to be the underlying theory of the strong interaction, which has three fundamental properties:chiral symmetry, color confinement, and asymptotic freedom. The perturbation theory may deal with behaviors of the strong interaction successfully in high energy region due to the asymptotic freedom. However, since the non-perturbative QCD in low energy region is very difficult to be solved, people still need various QCD-inspired models to help. Among this models, the chiral SU(3) and the extended chiral SU(3) quark models have obtained quite success in reproducing the energines of the baryon ground states, the binding energy of deuteron, and the nucleon-nucleon, the nucleon-hyperon, the nucleon-kaon scattering processes, and other systems with light quarks. Therefore, in this thesis, the chiral quark models are extended to the mesons and baryons with heavy flavors. Some interesting results are obtained by our primary studies. 1. With taking Yukawa form in one gluons exchange (OGE) potential, we have calculated masses of D, D*, Ds, Ds*, B, B*, Bs, Bs* mesons in the chiral SU(3) and the extended chiral SU(3) quark model by using the calculus of variations. The systematic model parameters for heavy quarks are obtained by fitting D, B experimental values, and interactions inside mesons are analyzed. The results show that OGE potential and confinement potential are attractive. When we keep the OGE coupling constant gQ unchanged, with the heavy quark mass mQ increasing, the attraction between Qq will increase, too. When mQ does not change, with gQ increasing the OGE between Qq will become more attractive, and the attraction of confinement will decrease.2. With takingδ(x) form in OGE potential, we have calculated energies of JP=1/2+ ground-state baryons including a heavy quark in the chiral SU(3) quark model by using the calculus of variations. Firstly, the model parameters for heavy quarks are achieved again by fitting experimental values of heavy mesons. The calculated results of baryonsΛQ,ΣQ,ΞQ are at most 90MeV higher than the experimental values. When confinement parameters are varied in a reasonable range, the numerical energies ofΣQ are well consistent with the experimental values, while those ofΞQ are about 50-70 MeV heavier. Most of results for AQ are very close to the observed ones. Interactions inside baryons are also discussed.