The Analysis Of Ripidity Correlation At The Rhic Energy S_NN^1/2=200GeV Au+Au Collision

From the physical knowledge that the current people have mastered, the basiccomposition units of matter is quarks and gluons. But because of the existence of quarkconfinement, until now it has not found a single free quark exists. Until the end of the20th century, physicists proposed, in relativistic heavy ion collisions, produces the highenergy density of the material——quark gluon plasma（QGP）. In the early low energyheavy ion collision, the existence of the short-range rapidity correlation has beenobserved. At the beginning of this century, Au+Au collisions at RHIC energy, you cansee the very strong long-range fast degrees of correlation. The multiphase transportmodel AMPT, is a very successful model to the analysis of the high energy heary-ioncollisions, and have got a very wide range of applications. Such as the study of theelliptical flow, HBT, as well as the final state partical rapidity distribution and so on.AMPT has two versions, the default AMPT, and the string melt AMPT. When the stringmelt AMPT model of scattering cross section is set to6mb, that can very good mesonrelevance in accord with the experimental data. So this article use the AMPT model tostudy the center-of-mass frame energy of200GeV of Au+Au collision, to analysis theForward-Backward multiplicity correlation strength with the different centrality and thedifferent rapidity interval, in order to detect the mechanism of the long-rangecorrelation.We will first discusses the experimentally measured results with200GeV AuAucollision data, and achieved that the long-range FB correlation increases with theincrease of the degree of the centrality; then the analysis of HIJING model is given, wecan see that it is very different between using the average method and the profilemethod. With average and profile two methods, this paper analyzes the AMPT model tosimulate the quality, and the center-of-mass frame energy200GeV Au+Au underdifferent degree of central collision data results. The results with average methods iscompletely opposite with the experimental data analysis results. And the results with theprofile methed, FB associated intensity with the tendency of the central degree and theexperiment data, however, the long-range correlation is opposite with the result of theexperiment data. And the correlation strength values sharply declining with the increase of the rapidity interval, it may reflects the CGC model and DPM model is correct todescribe the long range FB correlation from the side. But both of the two method whichwe can see the existence of long range correlation clearly, maybe we can say that thereare other reasons for the produce of the long range correlation.