Production And Correlation Of Final State Particles In High Energy Heavy Ion Collisions

Quantum Chromodynamics is a important theory to study strong interactions. It predicts that at extremely high temperature and high energy densities, hadronic matter will have a phase transition to form a new matter which consist of interacting quarks, antiquarks and gluons. This is quark-gluon plasma(QGP). For QGP only exist in a very short time, it can not be observed directly. So people try their best to find the QGP existing evidences both experimentally and theoretically.The investigation of QCD phase diagram is of crucial importance for our understanding of the properties of matter with strong interactions. QCD phase diagram is two dimensional diagram of parameters temperature(T) and baryon chemical potential(μB). Lattice QCD calcu-lations have predicted, at vanishing baryon chemical potential, the occurrence of a cross-over from hadronic phase to the deconfined quark-gluon plasma phase above a critical temperature of about170-190MeV. A distinct singular feature of the phase diagram is the QCD critical point which is located at the end of the transition boundary. Theoretical prediction showed that the third moment, called skewness, is proportional to ξ4.5and that the fourth moment, or kurtosis, proportional to ξ7while the second moment proportional to ξ2. More importantly, the moments are closely related to the susceptibilities of the thermal medium. Thus the higher order mo-ments have stronger dependence on the correlation length ξ and are therefore more sensitive to the critical fluctuations. It has been argued that the net-proton distribution can be a meaningful observable for the purpose of detecting the critical fluctuations of net baryons in heavy ion colli-sions. Based on theoretical and experimental investigations, it has been argued that information of QCD phase diagram and the critical point can be obtained from the energy dependence of those moments.We will introduce a simple model which only considering effects from initial baryon stop-ping and final baryon pair emission. These physics effects are well known from studying heavy ion collisions in the past decades. We show that such simple physics can be used to repro-duce the experimentally observed net proton distributions at different colliding centralities with parameters chosen properly. Then higher moments can be calculated numerically from the dis-tributions. For the tiny difference between Au+Au collisions and Cu+Cu collisions, their net proton distributions are different either.We disscuss the energy dependence of the parameters and give parametrizations for such dependence. And compare the dependence parameters for Cu+Cu collisions and Au+Au col-lisions. Then we explore the dependence to the CERN Large Hadron Collider energy and predict the net proton distributions for Pb+Pb collisions at different colliding centralities for (?)=2760GeV.The Ultra-relativistic Quantum Molecular Dynamics model(UrQMD) is a microscopic many body approach and can be applied to study hadron-hadron, hadron-nucleus and heavy ion colli-sions from SIS to RHIC. This microscopic transport approach is based on the covariant propa-gation of color strings, constituent quarks, and diquarks accompanied by mesonic and baryonic degrees of freedom. It simulates multiple interactions of in-going and newly produced particles. The new version of UrQMD includes hydrodynamic evolution.In high energy heavy ion collisions, the single particle density distribution in the final states exist fluctuations. These fluctuations have statistical and dynamical origins. The dynamical fluctuations can reveal some physics mechanism in the collisions. If the fluctuations under consideration are self-similar at all scales, the normalized factorial moments behave as an inverse power of the bin size. Large fluctuations in the final state particle density, particularly in nucleus-nucleus collisions, may be also an outcome of a transition from the exotic quark-gluon plasma to the ordinary hadronic phase. DFA and MFDFA can be good methods to study the non-statistical dynamical fluctuations in the single particle density distribution. It can remove the statistical fluctuations and retain dynamical ones. The one dimensional MFDFA has been investigated by using high energy nuclear emulsion experimental data. Because the actual process of particles production takes place in three dimensions, the effects of fluctuation are reduced or they can even be completely washed out when the dynamics is projected into a lower dimension. So in principle one should investigate the fractal properties of a colliding system in three dimensional phase space. In this paper, as an extension of the one-dimension methods, we use the DFA and MFDFA to study the dynamical fluctuations of particle distributions in two dimensional phase space by using different particles generated from the UrQMD code.In relativistic heavy ion collisions, People concern the system size and lifetime of QG-P. Hanbury-Brown-Twiss interferometry(HBT) is a well-estibated technique which is devel-oped to extensively used to determine the space-time and dynamic properties of the particle emission source. Longitudinal comoving system(LCMS) frame of the pair and "out-side-long" convention is usually choosed as the reference frame and convertion. Considering dif-ferent interactions in the final states, there has three different fitting procedure. We analyse HBT correlation properties of different particles which from UrQMD model.