Charged Particle Ratio Fluctuation And Higher Moments Of Net-Baryon Distribution In Relativistic Heavy Ion Physics

In the past century, Professor T. D. Lee pointed out that there were two puzzles in modern physics:one is the Missing Symmetry and the other is Unseen Quarks. As we all know, all hadrons are made of quarks, yet NO individual quark has been observed. At the same time, he predicted that via relativistic heavy ion collision, we can produce new form of matter consisting of deconfined quarks and gluons, at high temperature and low baryon number density. This new matter are named Quark-Gluon Plasma(QGP). This prediction promote the development of both theoretical and experimental studies. All of these work help us to gain more information of the QGP.After we stepped into the 21st century, the operation of Rela-tivistic Heavy Ion Collider (RHIC) bring us to the new era in the research of QGP. The results of back to back correlation suggested that the extreme dense matter had been produced. Also the elliptic flow "NQ" scalling behavior indicated that we had already measured the partonic collectivity at RHIC. In theoretical studies, lots of observ-ables are proposed to search for the existence of QGP. Among them, the event-by-event fluctuations are meaning approaches, especially the fluctuations of conserved quantities, like net charge and net baryon number, are regarded as useful tools to study the QGP. But in ex-periments the measured value of these observables seem different from theoretical predictions. In order to investigate the deviation of theo-retical predictions and experimental measured value, in this thesis we study the observable in different process. Comparing the measured value from each processes, we can study whether the fluctuation can provide the information from the partonic stage. All of our works are based on by Monte Calor models study.On the other hand, in quantum chromodynamics(QCD) phase di-agram, the transition between hadronic and partonic is first order at low temperature and high baryon number density; as the increase of temperature and decrease of baryon number density, the curve of first order phase transition ends at the critical point, at even higher temper-ature there is a crossover between partonic phase and hadronic phase. To map the components of the QCD phase diagram is one of the main goals of heavy-ion physics, and searching for the critical point has been addressed in both theoretical and experimental studies. Lattice calcu-lations and QCD based model studies predicted that higher moments of conserved quantities are sensitive to the characteristic of CP, in this thesis we study the acceptance effect and time evolution effects on higher moments of net baryon distribution, based on these works we can estimate wether these observables are good probes to locate the critical point.