随机初始条件下流体力学与微正则强子化在相对论重离子碰撞中的应用

直接光子是夸克胶子等离子体（QGP）的理想探针，一直因为容易受到衰变光子的干扰而不被采用。美国相对论重离子碰撞（RHIC）实验中PHENIX组开发了一种排干扰的方法，测得的直接光子横动量谱数据获得了广泛的理论解释，但是测得的直接光子椭圆流数据一直没有获得相应的理论解释。为了在欧洲的LHC实验上推广直接光子的测量方法，.我们拟采用已有的强子实验数据来建立可靠的重离子碰撞模型，来解释上述直接光子数据，并将模型向高能区(LHC能区)和低能区（RHIC能量扫描区域）拓展，用于更加广泛的研究。直接光子椭圆流的计算需要流体力学模型，而初始条件的随机性可能是解决上述问题的关键。由于初始条件的随机性和不规则性，通常采用的Coope－Frye公式进行Freezeout会出现一系列问题，我们准备用微正则系综的强子化方案来替代,使强子化研究这一重要问题上升到更高的水平。

Direct photon is an ideal probe of Quark-Gluon Plasma,while this probe is rarely used due to the polution of decay photons at low pt region. The Phenix collaboration at RHIC has developed a new technique to remove the polution from decay photons. However, their obtained elliptic flow data of direct photons can hardly be explained by now, while the corresponding transverse momentum spectra of direct photons are widely understood. In order to pomote the new technique of direct photon measurement, we plan to construct a reliable heavy-ion collision model based on a great deal of the relevant hadronic data, to explain the above-mentioned direct photon data. The produced heavy-ion collision model will be developed to both high and low energy region, ie, LHC region and RHIC energy scan region, for a wider research on hadronization and QCD phase diagram. The calculation of elliptic flow of direct photons must based on hydrodynamics, with a crucial factor, the radom initial condition.The random and irregular initial condition will make the whole evolution of the collision system more complicate and the freeze-out of final-state hadrons difficult. We would take microcanonical hadronization to replace the conventional Coope-Frye freeze-out, which can solve the technique problem and improve our understanding of QGP hadronization in heavy ion collisions.