Elliptic Flow Analysis At Rhic Enery With Different Methods

A major goal of relativistic heavy ion collisions is to exact information about properties of nuclear matter at high temperature and to obtain the nuclear equation of state.The collective flow of nuclear matter in the final state of the reaction is probably the most obvious manifestation of the nuclear equation of state in the experimental data.At RHIC,compared to radii flow and sidward flow,elliptic flow is more sensitive to the equation of state.Elliptic flow is related to the anistropy of the final particles in the momentum space.It is sensitive to the anistropy of the distribution of the particles in the early stage in the coordinate space and is an important quantum to detect the singal of the QGP.By now, many methods to calculate the elliptic flow are presented.They have different advantages and disadvantages.In this paper,using A Multi-Phase Transport(AMPT) model,the transverse momentum dependence of elliptic flow is presented from the Au+Au collision at the RHIC energy S_NN^1/2 200GeV.By converting the strings in the high energy regions into partons,we find that the final elliptiac flow is sensitive to the parton scattering cross section.We report the analysis of elliptic flow with different methods(Lee-Yang Zeroes method,event plane method,4-particle cumulant and two particle correlation method).The comparation of the results based on these methods and the real elliptic flow value denote sensitivity to the cross section and the partonic effects.When the parton scattering cross section is same,the change of the intension of the parton interaction leads to a corresponding change of the results based on these methods.They denote that these methods are sensitive to the partonic effects.The difference among these results also denote that they are sensitive to the partonic effects.This could reveal the different dynamical information.