Study Of QGP Hadronization

The study of the properties of strongly interacting matter under extreme conditions is the main subject of the heavy ion experiments.One of the goals of the experimental program of the Relativistic Heavy Ion Collider(RHIC)at Brookhaven and the Large Hadron Collider(LHC)at CERN is to produce and observe the plasma of deconfined quarks and gluons(QGP),which is expected to be a transient thermal system of interacting quarks and gluons.Several experimental signatures indicated that a deconfined state of matter was formed in heavy ion collisions.However,investigating the properties of QGP created in colliders is not an easy task because QGP cannot be observed directly.It is only possible to analyze the data of hadrons in the final stages of heavy ion collisions.Hence,in order to study the properties of the QGP,the numerical models that can describe the whole heavy ion collision should be established.This thesis focuses on the dynamical process of the phase transition,which is es-sentially needed,in order to have a complete physical picture of relativistic heavy-ion collisions and understand phenomena found in experiments.Firstly,we utilize B AMPS(Boltzmann Approach of Multi Parton Scatterings)model that numerically solves the Boltzmann equation with collision term to simulate the evolu-tion of gluons before phase transition.BAMPS model can work for the pre-equilibrium stage,the subsequent thermalization period and the succeeding QGP expansion stage.Then,we assume that the hadronization from gluons to pions is a first-order phase transition and give a detailed description of its corresponding numerical implementation.The volume change of gluons and pions during the phase transition is derived based on the conditions of phase equilibrium and hydrodynamical equations.With this,we obtain the probabilities of all the hadronization processes(from gluons to pions)during the first-order phase transition.In order to satisfy principle of entropy increase,we have considered 2?3 process(g+g??+?+?)in the numerical model.We compare the numerical results with analytical results to prove the numerical implementations.The comparisons show almost perfect agreements,which demonstrate the applicability of the numerical model we established.Finally,utilizing the equations of state of QCD matter and basing on the viscous hydrodynamics,we investigate viscous effects on the first-order phase transition.The relation between the viscosity and baryon chemical potential during the phase transition will be derived.A better understanding of the viscous effect on the phase transition can provide deeper insight into the physical mechanism of hadronization and provide a basis for further phenomenological studies.