Study of the Standard Model on the Lattice with Massively Parallel Computer CP-PACS

本项目使用完全O(A)改进的威尔逊-三叶草夸克作用和RG-改进的胶子作用，在三个晶格间距a=0.071fm，0.1fm和0.12fm，对所有三个轻夸克u，d，S的动力学效应进行了扩展的Nf=2+1格子QCD模拟。对轻强子能谱、轻夸克质量和重夸克物理进行了系统的连续外推。主要结果如下：(1)轻强子谱在猝灭的QCD中，介子和重子谱存在高达10%的系统偏差。目前的计算表明，在Nf=2+1计算中，这种偏差消失了，结果与实验在1%的水平上是一致的。然而，由于夸克在模拟中仍然相对较重这一事实引起的系统误差需要使用威尔逊手征微扰理论进行评估。初步分析表明它们与多项式外推是一致的。(2)轻夸克m…介子谱的结果使我们能够估计轻夸克的质量，对于轻夸克，我们发现在连续谱极限下，在μ=2GeV的MS方案中，u和d夸克的平均质量为m=3.49(15)MeV，S夸克的质量为m=90.9(3.7)MeV。这些值大约是现象学上广泛使用的值的2/3。(3)重夸克物理对项目成员提出的相对论重夸克作用进行了延伸测试。在非微扰调谐光速的情况下，在猝灭的QCD中对底原子谱和B介子衰变常数进行了实验计算，显示出良好的标度行为。在这一成功的鼓舞下，对动态Nf=2+1味组态的计算正在进行中。(4)未来展望这一项目的结果已经在格子研讨会和各种国际会议上公布。在本计算中遇到的一个限制是很难穿透到轻夸克质量区。对最近提出的区域分解HMC算法的应用进行了测试，并在新一代PACS-CS计算机上取得了令人鼓舞的结果。较少

This project carried out an extensive Nf=2+1 lattice QCD simulation including dynamical effects of all three light quarks, u, d, s using the fully O(a) improved Wilson-clover quark action and RG-improved gluon action at three lattice spacings a=0.071fm, 0.1fm and 0.12fm. Detailed study was made of the light hadron spectrum, light quark masses and heavy quark physics, taking a systematic continuum extrapolation. The main results are as follows :(1) Light hadron spectrumIn quenched QCD a systematic deviation of up to 10% is known to exist in the meson and baryon spectrum. The present calculation has shown that this deviation goes away in the Nf=2+1 calculations, the results showing an agreement with experiment at a 1% level. Systematic errors, however, arising from the fact that quarks are still relatively heavy in the simulations need to be assessed using Wilson chiral perturbation theory. Preliminary analyses show that they are consistent with polynomial extrapolation.(2) Light quark m … More assesThe meson spectrum results allow us to evaluate the light quark masses, for which we find in the continuum limit, m=3.49(15)MeV for the average of u and d quark mass in the MS scheme at μ=2GeV, and m=90.9(3.7)MeV for s quark. These values are about 2/3 of the phenomenologically widely used values.(3) Heavy quark physicsExtensive tests were made of the relativistic heavy quark action proposed by the members of the project. Test calculations in quenched QCD for the bottomonium spectrum and B meson decay constants with a non-perturbative tuning of speed of light showed excellent scaling behavior. Encouraged by the success, calculations on the dynamical Nf=2+1 flavor configurations are being made.(4) Future perspectiveThe results obtained in this project have been presented at Lattice Symposia and various international conferences. A limitation encountered in the present calculation is difficulty of penetrating into the light quark mass region. Application of the domain-decomposed HMC algorithm recently proposed has been tested, and encouraging results were obtained for their use on the next generation PACS-CS computer. Less