Study of the QCD phase diagram - Understanding of high-energy heavy ion collisions based on the first principle calculation and phenomenology

我们的主要目的是从高能重离子碰撞分析的角度研究夸克-胶子等离子体(QGP)的QCD相变动力学和详细性质。在2000年开始运行的相对论重离子对撞机(RHIC)上实现了强相互作用QGP(SQGP)的产生。根据相对论流体力学和复合模型，通过对实验数据的理解，确定了RHIC的sQGP的产生。此外，在大型强子对撞机(LHC)上，重离子碰撞的运行始于2010年。为了从RHIC和LHC高能重离子碰撞的理解中了解QGP的性质，我们进行了唯象研究。首先，我们将QGP的粘性效应考虑到流体+UrQMD模型中，该模型不仅能描述碰撞后热而致密物质的流体力学膨胀，而且还能描述强子之间的末态相互作用。本文提出了一种基于Godunov方法的求解相对论粘性流体力学方程的新算法。我们的数值方法具有以下重要性质：(1)数值耗散小，这对于分析实验数据中的物理粘度是很重要的。(2)处理逐个事件初始波动的冲击波捕获方案。结果表明，与其他算法(Shasta、KT和NT)相比，我们的数值格式具有较小的数值耗散。我们评估了包含我们的算法的数值耗散。现在，我们将该算法扩展到三维计算，并使用新的流体力学程序开始了对RHIC和LHC的实际计算。

Our main purpose is to investigate the dynamics of the QCD phase transition and detailed property of Quark-gluon plasma (QGP) from the point of view of analyses of high-energy heavy ion collisions. At the Relativistic Heavy Ion Collider (RHIC) which started its operation in 2000, the production of the strongly interacting QGP (sQGP) was achieved. The production of the sQGP at RHIC was established by understanding of experimental data based on relativistic hydrodynamics and the recombination model. Furthermore, at Large Hadron Collider (LHC) the operation of heavy ion collisions started in 2010. To get insight of QGP property from understanding of high-enegy heavy ion collisions at RHIC and LHC, we carried out phenomenological studies. First we include the viscosity effect of QGP into thehydro + UrQMD model which can describe not only the hydrodynamic expansion of hot and dense matter that is created after collisions but also final state interactions among hadrons. Here we developed a new algorithm that is based on the Godunov method for solving the relativistic viscous hydrodynamic equation. Our numerical method has the following important properties; (i) small numerical dissipation which is important for analyses of physical viscosity in experimental data. (ii) shock-wave capturing scheme for dealing with event-by-event initial fluctuations. We show that our numerical scheme has advantages over than other algorithms (SHASTA, KT and NT) in having smallnumerical dissipation. We evaluate the numerical dissipation that contains our algorithm. Now we extend the this algorithm to 3-dimentional calculation and start a realistic calculation for RHIC and LHC using our new hydrodynamic code.