流体动力学模型的两粒子压缩关联函数分析

高能重离子碰撞物理学的主要目的是利用探测到的末态粒子信息得到确实可靠的QGP形成证据.由于QGP只是在碰撞过程的某个极短瞬间存在,所以对核物质演化过程中媒介系统的研究是非常必要的,通过媒介系统的研究可以把分析QGP的探针深入到粒子冻出之前的媒介系统中.两粒子压缩关联函数通过媒介系统中准粒子与末态自由粒子之间的质量区别来反映准粒子与媒介系统的相互作用,利用非相对论流体动力学演化的火球模型,计算得到以两粒子平均动量为变量的压缩关联函数形式,选用和其他强子反应截面较小的介子模拟计算关联函数,计算结果表明小平均动量的介子来自于半径较大、径向膨胀速度较大的媒介系统,在温度和径向膨胀速度相同的情况下,两个介子的压缩关联函数对媒介系统半径变化不敏感.

The analysis of two-particle squeezed correlation functions in hydrodynamical model

The major goal of high energy heavy ion collision is to provide the accurate and reliable evidence for quark-gluon plasma （QGP） formation based on two detected particles information.Due to QGP instantaneous existence in collision,it is necessary to study the evolution of the strongly interaction dense medium,and it provides an important probe into the emitting sources before freezing out.We focus on two particles squeezed correlation functions arising from the difference of mass between the quasi-particles and observed particles related to the vacuum mass,and it reflects the interactions between in-medium quasi-particles and the dense medium.According to nonrelativistic hydrodynamical model of the system evolution,we develop the expression of two particles squeezed correlation functions as a function of the average pair momentum using a simple fireball expanding model.The two particles squeezed correlation functions are simulated by phi meson pairs which has less reaction cross section with other hadrons,and the results show that the phi mesons with small average pair momentum emit from the dense medium which has the big source radius and fast radial flow during the system expansion.The correlation functions are not very sensitivity to the change of the source radius corresponding to the same freeze-out temperature and the radial flow during the system expansion.