The Energy Loss And Collective Current Of Heavy Quarks In Relativistic Heavy Ion Collisions

QCD is a theory which can describe strong interaction.It predicts that QCD matter will undergo a phase transition from hadron to quark matter at high temperature and high density,forming a new form of matter:quark gluon plasma(QGP),in which quark can move freely in a large range.In recent years,the Relativistic Heavy Ion Collider of Brookhaven National Laboratory and the Large Hadron Collider of the European nuclear center have collected a large number of very valuable experimental data,and found a large number of signals supporting the existence of QGP,such as the collective current effect of the final hadron,which preliminarily proved the occurrence of QCD phase transition.The study of the properties of QGP in the laboratory is an important subject of high energy heavy ion collisions.Heavy flavor quarks,which are produced in the early stage of collision due to their large mass,are ideal probes for studying the evolution and thermodynamic properties of QGP.The distribution of heavy flavor quarks contains the basic information of nucleon structure,and the hadronization process depends on the distribution function of heavy flavor quarks.In this paper,we use the multiphase transport(AMPT)model,and add the heavy flavor quark generation enhancement mechanism in the initial stage of the model to describe the heavy flavor hadron production cross-section of experimental data,to study the detailed reaction process in the heavy ion nuclear reaction process.Through the elliptical flow study of the light flavor hadron,we find that The elliptical flow of light hadron is closer to the experimental data with the increase of the scattering cross-section from 3mb to 10mb in the AMPT model.Then we study the elliptical flow of charm hadron.We find that there are similar rules with light hadron elliptic flow.Then we study the two particle correlation function of heavy flavor quarks.obviously,it depresses in the region with an azimuth of 0,and increases in the region close to ?,which is obviously different from the known behavior of light flavor quarks and light flavor hadrons.Therefore,the azimuth correlation of heavy flavor quarks and heavy flavor hadrons is a new probe to study the QGP transport properties.In this newly developed AMPT model,we also study the elliptic flow of heavy flavor quarks and heavy flavor hadrons with the change of quark scattering cross section,and we find that the elliptic flow of heavy flavor hadrons increases linearly with the increase of scattering cross section.The settlement results with the scattering cross section of some of the particles of 10MB can describe the experimental data.It is found that with the increase of scattering cross section from 3mb to 10mb,the average number of collisions of quarks in AMPT increases from 4.5 to 8.5.Our study shows that the multiple cascade scattering of some quarks in AMPT is the key physical process for the formation of heavy quark and heavy hadron collective flow.Our results provide a new method for further study on the mechanism of heavy flavor hadron production and QGP fine properties.