Research On The Transverse Momentum Dependence Of HBT Radii In High Energy Heavy-ion Collisions

Intensity interferometry is an important method to extract the space-time and dy-namic information in the high-energy heavy-ion collisions,and the RHIC experiment has already published some interferometry results.The result shows that the HBT radii decrease with the increase of the pair-particles transverse momentum.This phenomenon is generally called the transverse momentum dependence of HBT radii.It is generally believed that the reason for this phenomenon is related to the single-particle space-momentum correlation.However,there is no detailed study on the space-momentum correlation,nor the specific process leading to the phenomenon at present.Therefore,this thesis mainly uses a variety of source models to analyze the transverse momentum depen-dence of HBT radii and quantitatively analyzes the relationship between single-particle space-momentum correlation and this phenomenon.The Monte Carlo method is used to establish the emission sources according to the emission source functions,and we use theparticles generated by these emission sources to analyze the intensity interferometry.The emission behavior of particles that no longer have interactions with others is named freeze-out,and the differences in the freeze-out time of those particles will affect the HBT radii.Thus we have limited the freeze-out time differences of particles in the thesis.In order to study the single-particle space-momentum correlation,we propose a quantitative analysis method by introducing the single-particle space-momentum angle distribution.Moreover,using a cylinder emission source,we find there is a numerical relationship between the single-particle space-momentum angle distribution and the transverse momentum dependence of HBT radii.These studies show that the space-momentum angle distribution can be used as a quantitative analysis method of space momentum correlation,and the distribution will directly lead to the transverse momentum dependence of HBT radii.In this thesis,we use the string melting AMPT to simulate the central Au+Au collisions.We study the space-time distribution of theemission sources and discuss how the partialsources change with the transverse momentum.The multi-transport AMPT model is a combined model that includes physical processes such as parton evolution and hadron interaction,and the string melting AMPT model can well describe the HBT radii.After that,we study the transverse momentum dependence of sideward HBT radius changes with the collision energies.It is found that the higher the collision energy can lead to more obvious the transverse momentum dependence of sideward HBT radius.On the transverse plane,we optimize the fitting function of the normalized single-particle space-momentum angle distribution and establish a numerical model between the normalized single-particle space-momentum angle distribution and the transverse momentum dependence of sideward HBT radius.And the model is helpful to study the single-particle space-momentum correlation.In order to apply the numerical model between the single-particle space-momentum angle distribution and the transverse momentum dependence of HBT radius to the exper-iments,we also need to consider the influence of Coulomb interaction on the correlation functions.Therefore,with focusing on the~+mesons in the Au+Au collision simulated by the AMPT model,we discusse the influence of Coulomb interaction on the sideward HBT radius and find that Coulomb interaction will inhibit the transverse momentum dependence of sideward HBT radius.Then we study the effect of the single-particle space-momentum angle distribution on the~+sources and study the influence of no single-particle space-momentum angle correlation on the HBT radii.Moreover,we modify the parameters in the numerical model by studying the influence of Coulomb interaction on the numerical model between single-particle space-momentum angle distribution and the sideward HBT radius transverse momentum dependence,it makes the model improved and developed.