The Study Of Coupled Channel Effects In The Decays Of Heavy Quarkonium-like States

In recent years, many heavy quarkoniumlike states have been discovered by experiment,and the production and decay of such states may have great significance for studying nonperturbative nature of Quantum Chromodynamics (QCD). Within the framework of effective Lagrangian approach and intermediate meson loop model, we have studied the productions and decays of several heavy quarkoniumlike states combine with the resent experiment.This thesis first introduce the development history of the particle physics and four fundamental interaction. In the research method part, we first introduce the fundamental theory of strong interaction--Quantum Chromodynamics, then introduce the effective field theory which is used for dealing with low-energy physics and nonperturbative effects. At last, we introduce the intermediate meson loop model. The research content consists the following two parts:Firstly, we study the light hadron decay process of Zc (3900) and Zc (4025). The experiment has been measured their masses, widths, quantum numbers and the main decay channels of Zc(3900). Under the molecular state ansatz, we calculate the branching ratios of Zc (3900)/Zc (4025) ?VP(V and P denote the light vector and pseudoscalar meson) which may be measured by the experiment in the future. Strong decays of charmoniumlike states has three important modes commonly: hidden charm decays, open charm decays, c(?) annihilation.The first two decay modes involve with threshold effect, the last one is an unique signature of strong decays of charmoniumlike states. Whether the non-observation of Zc(3900)??? on experiment, or the calculated small branching ratios, both indicate that the annihilation of c(?) in the strong decay of Zc may be suppressed to some extent.Secondly, we study the production of Xb in ?(55,6S)??Xb radiative decays, where Xb is assumed to be the counterpart of X (3872) in the bottomonium sector. We use the effective Lagrangian based on the heavy quark symmetry to explore the re-scattering mechanism and calculate their production ratios. Our results have shown that the production ratios for?(5S,6S) ??Xb are orders of 10-5 with reasonable cutoff parameter range ?; 2: 3. In addition, we also calculate the branching ratios of the decays in the framework of non-relativistic effective field theory, the calculate results of these two methods basically consistent.Finally,I present a summary of this thesis and prospects for future research.