The Study On The Issue Related To Multiquark States Production In High Energy Reaction

Searching for new physics beyond the Standard Model(SM)and solving the non-perturbative problem of Quantum Chromodynamics(QCD)are two major issues faced by current particle physics.SM has been fully verified by many experiments since it was established.However,many problems still remain unsolved within SM framework.The Perturbative Quantum Chromodynamics(PQCD)can be used to accurately calculate the hard-scattering process with large momenta transfer,i.e.,the parton(quarks and gluons)level reactions in the high-energy region,but for the soft processes such as hadronization in the low-and mid-energy region,the PQCD is no longer applicable,and it can only be dealt with some methods of non-perturbative approximations including lattice theory,QCD sum rule,and phenomenological quark model etc.The internal structure of hadrons is a topic closely related to Non-perturbative Quantum Chromodynaimics(NPQCD).It is one of the basic tasks of particle physics to explore the internal structure of hadrons.In the past few decades,the number of exotic particles beyond the traditional quark model discovered experimentally has increased dramatically.In order to understand their essence,people have proposed various theoretical models,such as glueball,multi-quark states,hadron molecule,and hybrid states.However,none of the models proposed so far can provide a con-vincing explanation for the emergence of such kind of new hadron states.The deep exploration of the process of hadronization by heavy flavor hadrons,es-pecially by multi-quark hadrons,is an important means to study the mechanism of strong interactions,test the standard model,and understand the confinement mech-anism.As the simplest quark systems,mesons and baryons are important basis for understanding low-energy QCD,but they can hardly provide information about rich color structures of QCD,because their color structures are uniquely determined.To obtain more color structure information,one must study the multiquark system in which the color structure is not unique,so that we can have a better understanding of the low-energy behavior of QCD and also conduct a more extensive inspection of the QCD model.Among the current non-perturbation approximation methods,although the lattice gauge theory and the QCD sum rule are based on the first principle of QCD,due to the complexity of calculation,they both encounter great difficulties in describing hadron interactions and multi-quark states.Therefore,the phenomenological model is still the most effective method to study the multi-quark state hadronization.Focusing on the above issues,we mainly does the following works:· Study of new bound states production in high energy hadron-hadron colli-sions.The non-relativistic wave function framework is applied to study the production and decay of exotic hadrons,which can be effectively described as bound states of other hadrons.Employing the factorized formulation,with the help of event generators,we investigate the production of exotic hadrons in multi-production processes at high energy hadron colliders.Based on our calculation,one can go further to estimate the kinematic distributions of the signal particles which are from the decay of X(5568)and can be directly de-tected.This study provides crucial information for the measurements of the relevant exotic hadrons.·Study of multi-quark hadron production in high energy e?e-annihilation re-action.We study a special color connection of four-quark system which favors the production of XYZ particles.Taking X(3872)as an example,we discuss the hadronization of this special color connection,and use the Lund String Fragmentation Model(LSFM)to study the corresponding hadronization ef-fect during the e+e-annihilation process.The most important case is the production of double heavy baryon/tetraquark and some new bound states in the 3-jet like events.In addition,for the 3-jet case,the string effect of the special particle stream can also be used to explore the color connection more precisely.We study one possible production mechanism for the compact hidden-charm pentaquark via a color-octet cc pair fragmentation in e+e-collision with clean backgrounds.The most straightforward application of our analysis is the B factory at present and in the future.According to our calculations,at B factory energies,the dominant production process is e+e-? ccg Pc + X.This means Pc is dominantly produced in a two-jet like event.While at Z0 pole energy,there are several partonic processes playing significant role.Our results show that it is possible to search for the direct pentaquark production signal at e+e-colliders,which is important to understand the properties of pentaquark.· In the above studies,the phase-space correlations of two or more hadrons associated with various high-energy multi-production are of great significance for the further study of the mechanism and structure of hadronic molecules.Therefore,it is worth investigating in both experiments and phenomenological theory in the future.We combine the inconsistencies of the observation results of X(5568)production by different experimental groups,and further study the correlation and invariant mass spectrum of the two ingredient particles Bs0?±.These results provide a reference for understanding the differences between different experiments.