Studies On Production Of Exotic Hadron In High-Energy Multiproduction Processes

The structure of hadron and related problems have always been the forefront of theoretical and experimental research in particle physics.Through a large number of experiments,it has been confirmed that quarks and gluons are the basic particles that make up the hadrons,and they can not be separated from the hadrons,that is,the "confinement effect" of strong interaction.Using quantum chromodynamics(QCD),we can carry out reliable perturbative calculation for the phenomenon and process of high-energy scale,and the problem of hadronic structure inevitably involves low-energy scale,and the perturbation method is no longer applicable.So we can only use other methods to study hadronic structure,such as lattice QCD,effective field theory and QCD sum rules and so on.Many phenomenological models,such as static quark model,bag model,string model,and the regge model(soft process)and parton model(hard process)combined with different high energy scattering processes,have also been proposed.The above phenomenological models are closely related to QCD in different aspects,which embody some important features of QCD,and have their own advantages in explaining the different phenomena of hadron physics.At the same time,the existence of so many models also means that we still need to further explore the essence of strong interaction and QCD.In addition,strong interaction is a color interaction.When the hadronic process is studied in a model,the specific model must first use parton system with a definite color state.Therefore,exploring the hadronic results given by different color states will also provide important information for revealing the internal structure of the hadron and understanding the color confinement mechanism.This dissertation focuses on the frontier of the generation and structure of exotic hadronic states,especially exotic hadronic states with heavy flavor quarks.Because of the special superiority of the heavy quark production process,there are two main advantages,one is that such a process is easily resolved by the experiment,and the other is the corresponding part of the sub level event shape,which can effectively provide the conditions for the experiments.In recent years,a large number of exotic hadronic states have been discovered in experiments.A series of special properties make it rapidly become the focus of theoretical research.Especially in early 2016,D0 experiment gave for the first time that the significant signal of exotic hadronic state may be generated in the multiproduction process of high-energy proton-antiproton collisions.Combining this process to study the production mechanism,not only can we obtain the information needed for the measurement of the cross section and various kinematic distributions,but also reveal the internal structure of exotic hadron state.Therefore,the main work of this paper is to describe the generation of hadronic molecular states by using the non-relativistic effective theory to describe the generation mechanism of the exotic hadronic state,reveal the internal structure and properties of the hadronic States,and understand the hadronic mechanism and the nature of the color confinement.There are many ways to study the generation of exotic hadrons in high-energy multiproduction.One of the prominent characteristics of the hadron molecular state is that the binding between the traditional hadrons is looser and the relative momentum of each other is smaller than the hadron mass,so the hadron molecular state can be considered as a non-relativistic system in principle.Based on this fact,we developed a set of theoretical formula,and used non-relativistic effective theory to describe the universal generation of hadronic molecular states.This method has many advantages,for example,when the hadron is the basic degree of freedom,any research object is a color-singlet state without color confinement and the complexity caused by the consideration of the color octet.In high energy collisions,once the production rate of molecular states is obtained by the method of non-relativistic effective theory,the useful information such as the distribution of rapidity and transverse momentum can be obtained,which provide important information and possible selection conditions for the current and future experiments on the measurement of exotic hadronic state.