Two-body Strong Decay Behavior Of ρ/ρ₃ Mesons And S-wave Charmonia

Quantum Chromodynamics (QCD) is a non-Abelian gauge theory that describes strong interaction in the standard model. Because of the self-interaction of gluons, QCD is much more complicated than Quantum Electrodynamics (QED). At high energy, the traditional perturbation theory can be used to calculate strong interaction since the run-ning coupling constant is small, and many problems can be solved effectively. However, the traditional perturbation theory is no longer applicable at low energy for the coupling constant becomes large. Besides the lattice gauge theory that can be applied to calculate strong interaction at low energy numerically, various phenomenological models are the effective way to deal with this issue. Studies on meson spectrum and decay behavior can provide important information of the dynamics of quarks and gluons, which is helpful to improve our understanding of QCD. Recent fruitful progresses in experiment on hadron physics provide us good opportunities to understand QCD theoretically.Quark Pair Creation (QPC) model is one of the models widely used to calculate two-body strong decay of hadrons. Based on the this model, we studied the decay behaviors of ρ/ρ3 mesons and S-wave charmonia.At first, we systematically study these observed ρ/ρ3 states. The analyses of Regge trajectory of mass spectrum and two-body strong decay behavior show that ρ(1450), ρ(1900) and ρ(2150) can be radial excitations of ρ(770) while ρ(2000) and ρ(2270) are the first and the second radial excitations of ρ(1700) in the ρ(3D1) meson family. In addition, ρ3(1690), ρ3(1990) and ρ3(2250) states can be categorized into the p(3D3) meson family. However, for ρ(1700) and ρ3(1690), there exist discrepancies between our results and experimental data. We hope future experiments can get more precise results of resonance parameters and partial decay widths. The study presented in this thesis also gives abundant information of the decay behavior of these discussed p/p3 states and some branching ratios, ratios of some partial decays, which will be helpful to further study these states experimentally.Secondly, inspired by the similarity between mass gaps of J/φ and γ families, the prediction of a missing higher charmonium with mass 4263 MeV is made. Through our calculation, we find that its width is very narrow. In addition, the properties of two charmonium-like states, X(3940) and X(4160), and charmonium^(4415) are discussed, where our calculation shows that X(3940) as ηc(3S) is established while the explanation of X(4160) to be ηc(4S) is fully excluded and that ηc(4S) is typically a very narrow state. These predictions can be accessible at BESIII, Belle and BelleⅡ in near future.