2+1 flavor lattice QCD toward the physical point
2+1 flavor lattice QCD toward the physical point
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DOI：
10.1103/physrevd.79.034503
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发表时间：
2009-02-01
影响因子：
5
通讯作者：
Yoshie, T.
中科院分区：
文献类型：
--
作者：
Aoki, S.;Ishikawa, K. -I.;Yoshie, T.
我们给出了PACS-CS计划的第一个结果，该计划的目标是在物理点上用O（a）非微扰改进的Wilson夸克作用量和Iwasaki规范作用量模拟2 + 1味格QCD。在32（3）× 64格点上，用区域分解HMC算法对β = 1.9（对应于格点间距a = 0.0907（13）fm）的上下夸克质量进行了数值模拟.进一步的算法改进使上下夸克质量与物理量一样轻的模拟成为可能。由此产生的赝标介子质量范围从702 MeV下降到156 MeV，这清楚地表明存在手性介子。用SU（3）手征微扰理论分析赝标介子扇形，发现在物理奇夸克质量下，次领先阶修正很大。为了估计物理上下夸克质量，我们采用SU（2）手征分析，将奇异夸克的贡献在物理奇异夸克质量附近解析展开。SU（2）在杆（3）上的低能常数（l）和杆（4）上的低能常数（l）与最近由其它格点QCD计算得到的结果是相当的。我们使用m（π）、m（K）和m（Ω）作为输入来确定物理点以及晶格间距。外推到物理点的强子能谱与实验值在百分之几的统计误差水平上一致，尽管仍然存在可能的截止效应。我们还发现，当重整化在一个环上进行微扰时，f（pi），f（K）及其比值的结果与实验值是一致的。对于物理夸克质量，我们从轴矢量Ward-Takahashi恒等式和微扰重整化因子中得到m（ud）（（MS）over bar）和m（s）（（MS）over bar）.我们还简要讨论了静态夸克势的结果。
We present the first results of the PACS-CS project which aims to simulate 2 + 1 flavor lattice QCD on the physical point with the nonperturbatively O(a)-improved Wilson quark action and the Iwasaki gauge action. Numerical simulations are carried out at beta = 1.9, corresponding to the lattice spacing of a = 0.0907(13) fm, on a 32(3) X 64 lattice with the use of the domain-decomposed HMC algorithm to reduce the up-down quark mass. Further algorithmic improvements make possible the simulation whose up-down quark mass is as light as the physical value. The resulting pseudoscalar meson masses range from 702 MeV down to 156 MeV, which clearly exhibit the presence of chiral logarithms. An analysis of the pseudoscalar meson sector with SU(3) chiral perturbation theory reveals that the next-to-leading order corrections are large at the physical strange quark mass. In order to estimate the physical up-down quark mass, we employ the SU(2) chiral analysis expanding the strange quark contributions analytically around the physical strange quark mass. The SU(2) low energy constants (l) over bar (3) and (l) over bar (4) are comparable with the recent estimates by other lattice QCD calculations. We determine the physical point together with the lattice spacing employing m(pi), m(K) and m(Omega) as input. The hadron spectrum extrapolated to the physical point shows an agreement with the experimental values at a few % level of statistical errors, albeit there remain possible cutoff effects. We also find that our results of f(pi), f(K) and their ratio, where renormalization is carries out perturbatively at one loop, are compatible with the experimental values. For the physical quark masses we obtain m(ud)((MS) over bar) and m(s)((MS) over bar) extracted from the axial-vector Ward-Takahashi identity with the perturbative renormalization factors. We also briefly discuss the results for the static quark potential.