The Anisotropic Flow Of Final Hadrons In EPOS Model

The development of high-energy collision and nuclear physics make human has a new understanding for material’s emergence and evolution, namely that the ordinary hadronic matter may be lifted closed phase change under the condition of high temperature and density, and then forming a quark-gluon plasma, which can be read QGP. And high energy heavy ion collision physics is the important way to solve and prove this conjecture, the purpose of high energy heavy ion collision experiment is to find the material existence, and then thus inversion with hadronic matter to quark-gluon plasma material real phase change process and contains the laws of physics.Relativistic heavy ion collision test is make two flight particles accelerated to nearly the speed of light to collision, and then at some point after be gathered in a small space for an instant a huge amount of energy so that gluons and quarks released from the nucleus, closed and because gradual freedom makes them become very weak interactions between the forming a quark-gluon plasma (QGP). After many times experiment in RHIC, physicists realize a variety of signal for QGP produce. Such as the double lepton and large transverse momentum of directly photons produced、The decrease of J/Ψ and the increase of strange particle、Jet and quenching effect、and the phenomenon of collective flow.The main content of this paper is to use the 3+1d fluid mechanics model namely the EPOS model of Monte Carlo simulator to simulate nuclear-nuclear collision, the main process is high energy collision of Au-Au collision, Through the statistical and analysis the pseudo-rapidity density distributions(dN/dη)、Transverse momentum distributions((?)) and the anisotropic flow distribution of final particles that we can conclude and inversion the early physical evolution process of high energy nuclear-nuclear collision. The main purpose of those is give a help for experimental physics and theories physics through the phenomenological physical simulation study.From the pseudo-rapidity density distribution of final hadrons, we can conclude that the number of hadrons is depending on the collision energy and centrality. Although the number of final hadrons is independent of energy and centrality in forward and backward rapidity area, In the middle area, the higher of collision energy or centrality, the many final hadrons will be produced. Meanwhile, from the transverse momentum distributions of final hadrons, we can see that particles with large transverse momentum are far less than particles with small transverse momentum, which can be understood as when quarks and gluons through the hot dense material, only the particle who has high energy can still has high transverse momentum to be accepted by detector after crossing the fireball. While the collective flow of final hadrons is formed due to the interaction between particles, and it reflects the overall motility of final state particles, and it only exists in the early time of collision, so study the collective flow of final particles can provide important information to proof QGP is produced.To study some properties of collective flow, we will use two kinds of methods to calculation the flow in this paper:event plane method and 2-particle cumulative moment method to calculate the data from epos model. We found that collective flow is influenced with initial state statistical fluctuations as we study the collective flow, so when use event plane method to estimate flow, a revise is needed. At the same time, in order to reduce the influence of the flow, we use the cumulative moment method rather than a single azimuth correlation method for calculation. Finally, we found that the collective flow of final hadrons depends not only on transverse momentum but also centrality, more head-on collision, smaller of the collective flow. It also suggests that the asymmetry of coordinates in space is much smaller at the initial time, the less of the collective flow.