Study Of Strange Particles’ Ratio By Statistic Model

Quark-Gluon Plasma(QGP), is the most expected matter phase predicted by the Quantum Chromodynamics which was established to describe the quark matter. What on the earth can help us to create and find such a matter phase is Relativistic Heavy-ion Collisions. But we can not observe such a hot and dense matter directly,the only way we can do to know its property is to measure the various yields after the collision and infer the connection between QGP and the measured quantity. It is necessary to build a model which can describe the collision well. A thermal statistic model is to be thought appropriate and reasonable since the large number of the involved nucleons and,accordingly, the yields of the collision.Strange quark,which is "the second generation of quarks",is a very well prob to detect the QGP, because of its long "life" compared with the collision time scale and its abundance.For example,we can measure the ratio between the strangeness particles and the un-strangeness particles then compare this ratio with thus in the nucleon-nucleon collision to determine whether QGP is formed or not.In this paper, we research the energy dependence of various hadron ratios,p/π, k/π, Λ/π, ?/π, Ω/π. The energy ranges from 1GeV to 10TeV covering from SPS to LHC. Then we compare the thermal model fit results with the data from experiments and point out that the "peak" shown in the strange particles to π ratios can be explained well in the framework of statistical model.We discuss that when we change the baryon to charge ratio in the fit,considering the proton fragmentation in the collision,the peak displayed in k/n energy-dependent figure will be sharpen. We find some deviation between calculations and data when the center-energy becomes larger in STAR. Then we change some parameters simulating the Pb-Pb collision whose center-energy is 2.76TeV and compare the result to the data and discuss some deficiencies in statistic model.