The Charge-charge Balance Functions And System Chemical Evolution In Ultra-relativistic Heavy-ion Collisions

The ultra-relativistic heavy ion collisions run at RHIC and LHC provide scientists with a promising tool to investigate the properties of quark gluon plasma(QGP). Scientists believe that quark gluon plasma was created in the heavy ion collisions conducted at RHIC and LHC. But the knowledge on the production mechanism of quark gluon plasma,the evolution and hadronization of quark gluon plasma, the evolution process at hadronic stage need to be improved in near future. The charge-charge balance function is an important tool used to study the creation and evolution of quark gluon plasma. People realized that the formation of strong charge-charge correlation in central collisions requires a process at which the quark and gluon interact with each other sufficiently. The strong chargecharge correlation in central collision was believed as an important signal of quark gluon plasma. The charge-charge balance function is sensitive to the time at which charges are created, the form with which charges exist, the diffusion of charges and the hadroniztion of quark gluon plasma and can be used to detect the dynamical process in ultra-relativistic heavy ion collisions. In this work, we will study the properties of charge-charge balance function and system chemical evolution in ultra-relativistic heavy ion collisions.RHIC experimental results tell that the created quark gluon plasma is a strongly interacting system. People studied the hadronization mechanism of this strongly interacting quark gluon plasma and found that binary or three body bound states exist in the strongly interacting system with the temperature around ????possibly. The fact that the values of??????(??) calculated by Lattice QCD are nonzero at temperature around ????also indicates the existence of bound states. Thus, it is necessary to study the signal of QGP quasi-particle model including variant bound states. We will consider the existence of all different kinds of binary and three body bound states in QGP, calculate the contribution of binary and three body bound states to the QGP’s ??QGP????. And we will study the contribution of binary bound states and three body bound states to the balance functions of ??+??-、??ˉ??、????-.The chemical evolution in ultra-relativistic heavy ion collisions is always the issue people focus on. Using the equation of state calculated by Wuppertal-Budapest QCD Collaboration, we get the temperature field and velocity field of QGP system by solving relativistic hydrodynamic equations. We study the chemical evolution of quark gluon plasma using the relation between quark number fluctuation ??????(??) and quark number density with the help of temperature field and velocity field of QGP system. We simulate the chemical evolution of hadronic gasses by overriding the hadronic reactions on hydrodynamic expansion of hadron gasses and stress the chemical evolution of ??、??、??、Λ、Σ、Ξ、? particles after considering the baryon annihilation process ?? + ˉ?? 5??.The proper time dependance of particle densities, the temperature of hadronic gasses, the particle chemical potentials are calculated. The effect of inverse process 5?? �' ?? +ˉ?? on the chemical evolution of hadronic gasses is also studied.Theoretically, the number of quarks and gluons continue to change until the chemical freeze-out of quark gluon plasma. For this reason, we investigate the balance functions in continuing quark creation scenario. We combine the boost invariant longitudinal(The direction in which two nucleus collide) expansion with the transverse cylindrical expansion to describe the expansion of quark gluon plasma. The fluctuations????????(??) varying as a function of time ?? can be calculated by combining the quark susceptibilities calculated by the Wuppertal-Budapest Lattice QCD collaboration, which vary as a function of temperature, with the temperature and velocity of source. We develop balance functions under two-wave scheme of quark production proposed by Scott Pratt to the formalism including charge-charge correlation created at all the time before chemical freeze-out. The effect of charge diffusion on the charge-charge balance functions is also investigated by implementing the hyperbolic diffusion equations. We study the effect of different creation patterns between light quark and strange quark on the width of ??+??-、??+??- balance functions.