| Quantum chromodynamics(QCD) is generally believed to be the fundamental theory of the strong interaction. High energy processes are calculable due to the asymptotic freedom of QCD. The low energy phenomena, for example, the properties of hadron and hadron-hadron interaction, are however difficult to be calculated directly from QCD due to the infrared confinement and the complexity of QCD. Various QCD-inspired models have been developed to study the properties of hadron and hadron-hadron interaction. The constituent quark model is the most used one. Not only it can be used to discuss the ground state hadrons, but also the excited state of hadrons, and it also can be easily extended to hadron-hadron interactions. The nonrelativistic quark model, in which the one-gluon exchange interaction is considered as the residual interaction between the confined quarks, developed by Isgur and Karl reproduced the baryon properties very well. After some extension, the model can also be used to describe the properties of deuteron and nucleon-nucleon interaction. The model can provide us much more information of QCD and strong interaction.Meson is the ideal place for us to study the QCD and strong interaction. First it is the simplest strong interaction system, secondly the meson spectroscopy, from few hundreds MeV masses of light pseudoscalar mesons to 10GeV of bb|- systems, span a wide energy region allows us to address perturbative and nonperturbative phenomena of QCD. A lot of work have been devoted to meson spectrum and there are a lot of progress. However there are still some problems exist. The pseudoscalar mesons and scalar mesons (f0(600), f0(1500)) are difficult to be accommodated by qq|- description. Recently there are a lot of interests on the tetraquark system because B factories revealed signals of tetraquark. The "appearance" of tetraquark provide a new challenge for the meson spectroscopy, since the tetraquark stateshave the same quantum numbers as qq|- system in most case. To identify a tetraquark state, first one has to ensure the state cannot be described by qq|-. And also the model used to study tetraquark system should be constrained by meson spectroscopy and meson-meson interaction. In this work, the nonrelativistic constituent quark model is used to study the meson spectroscopy. The model is based on Isgur-Karl model, the Goldstone-boson-exchange interaction are introduced between quarks due to the spontaneous symmetry breaking of QCD in the low energy region. So the interaction between quark and antiquarks consists of confinement, one-gluon-exchange and Goldstone-boson-exchange terms. The mass of meson is calculated by solving the Schrodinger equation numerically. The calculated results show that the model can describe the meson spectroscopy very well, including the pseudoscalar mesons, which believed to be the Goldstone bosons. The mixing betweenηandη' can be described well by K meson exchange. Some scalar mesons (f0(600), f0(1500)) and the states discovered recently by experiments (X (3872), Y(4260)) can not accommodated by qq|- description. The mixing between qq|- and tetraquark may be needed, the work is in progress. |
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