Quark-Gluon Systems at Extreme Condition: International Collaboration for High Temperature and Density QCD

1)在RBHIC，创造了一种新的物质形式。通过格子QCD这一第一性原理计算来理解这一新物质是很重要的。我们用格子QCD详细计算了夸克-胶子等离子体的剪切粘性，发现它很小，物质几乎是理想流体，这是实验所建议的。2)我们进行了上述计算，结果表明，体粘性很小，但是正定的。3)我们计算了禁闭和解禁闭阶段的夸克传播子。我们观察到在禁闭阶段光谱不是正定的。夸克质量在禁闭阶段和解离阶段是不同的。特别是在退禁闭阶段，标准形式不起作用。4)在很高的温度下，禁闭有望被打破。要理解这一现象，重要的是要了解零温度下的限制机制。为此，我们利用库仑规范这一物理规范，对色库仑形式进行了数值计算。我们观察到禁闭力来自色-库仑力，并且与Fadddev-Popov算符的本征值的行为有关。然而，本征值的温度行为与预期的不同，即本征值在零附近的凝聚不会消失。5)我们在高性能计算机的新体系结构CELTLL上开发了一种格子QCD码。

1) At RBHIC, a new form of matter was created. It is important to understand this new matter by lattice QCD, the first-principle calculation. We calculated the shear viscosity of quark-gluon plasma in detail by lattice QCD and found that it is very small and the matter is almost perfect fluid, which is suggested by experiments.2) We proceed the above calculation, and showed that the bulk-viscosity is very small but positive definite.3) We calculated quark-propagators in both the confinement and the deconfinement phases. We observed that the spectrum is not positive definite in the confinement phase. Quark mass is difkent in the confinement and deconfmment phases. Especially in the deconfinement phase, a standard form does not work.4) At very high temperature, the confinement is expected to be broken. To understand this phenomena, it is important to understand the confinement mechanism at zero temperature. For this purpose, using the Coulomb gauge, which is the physical gauge, we calculated the color-Coulomb form numerically. We observed that the confinement force comes from the color-Coulomb force, and relates to the behavior of eigen values of the Fadddev-Popov operators. However, the temperature behavior of the eigen values is different from what was expected, ie., the condensation of the eigen-values near zero does not disappear. The confinement/deconfinement transition is very non-trivial.5) We developed a Lattice QCD code on the CELTLL which is a new architecture of high-performance computers.