NUMERICAL STUDY OF LATTICE QCD WITH THREE DYNAMICAL QUARKS

三动态夸克晶格QCD的数值研究

基本信息

批准号：
13640259
负责人：
UKAWA Akira
金额：
$ 1.79万
依托单位：
UNIVERSITY OF TSUKUBA
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640259/
关键词：
LATTICE GAUGE THEORY LATTICE QCD NUMERICAL SIMULATIONS QUARK PHASE TRANSITION CLOVER ACTION MONTE CARLO METHOD PERTURBATIVE EXPANSION

项目摘要

This work aimed to develop methods for lattice QCD simulations including dynamical strange quark in addition to dynamical up and down quarks. The main results we have obtained are as follows.1. Algorithm developmentTreating odd number of dynamical quarks requires an algorithmic development. We have shown that the polynomial HMC, in which the inverse of a single Dirac operator needed for the strange quark is approximated by a polynomial, provides a viable method for this purpose. We have also extended the algorithm to the Kogut-Susskind action, and has formulated an exact PHMC algorithm for it; such an exact algorithm had not been known before.2. phase structure of three-flavor lattice QCDWe have applied the algorithm to study the phase structure for three-flavor lattice QCD at finite lattice spacings. It was found that the combination of the plaquette and clover quark action develops a line of first-order phase transition which is a lattice artifact. While the transition terminates bef … More ore reaching the continuum limit, the lattice spacing at the termination point turned out to be about 4GeV. Since we need to start simulations closer to the continuum limit to avoid unphysical effects of such phase transitions, the plaquette-clover combination appears impractical for carrying out actual simulations. Switching the gauge action to an RG-improved action, it was found that the phase transition disappears, presumably because gauge field fluctuation becomes more continuum-like for improved actions.3. Determination of the clover coefficient for RG-improved gauge actionTo carry out a continuum extrapolation using lattice spacing 1/a=1-2GeV, an O (a) improved action is needed. Since the clover coefficient for the RG-improved gauge action is not known, we have decided to apply the Schrodinger functional method for this purpose. It turned out that O(a/L) errors need to be controlled precisely for this purpose, since bare gauge coupling is large. We treated this problem through simulations with a fixed L(in physical units), and determined the clover coefficient as a function of the bare gauge coupling.4. Physics runsAs a first step toward realistic three flavor QCD simulations, we have started runs at l/a=2GeV using 16^3x32 lattices. We plan to carry out the light hadron spectrum run, followed by determinations of light quark masses and the QCD coupling constant. Further work on heavy quark physics shall utilize gauge configurations generated in those studies. Less

这项工作旨在开发用于晶格QCD模拟的方法，包括动态奇怪的夸克，除了动态上下夸克。我们获得的主要结果如下1。处理奇数动态夸克的算法开发需要算法开发。我们已经表明，多项式HMC，其中奇怪夸克所需的单个狄拉克操作员的倒数由多项式近似，为此目的提供了一种可行的方法。我们还将算法扩展到了Kogut-susskind动作，并为其制定了精确的PHMC算法。这种确切的算法以前尚不知道2。三量晶格QCDWE的相结构已应用该算法来研究有限晶格间距下三培料晶状体QCD的相结构。发现Plaquette和Clover Quark Action的组合形成了一阶相变的线，这是晶格伪像。尽管过渡终止了BEF…更多的矿石达到了持续的极限，但终止点的晶格间距被证明约为4GEV。由于我们需要启动模拟更接近持续极限以避免这种相变的非物理效应，因此对于进行实际的模拟，plaquette-clover-clover组合似乎是不切实际的。将量规动作切换到RG改良的动作，发现相变的消失，可能是因为量规场波动变得更加连续性，以改进动作。3。使用晶状体间距1/a = 1-2GEV来确定RG改进的量规动作的三叶草芯FFF，以进行连续外推，需要改进的动作。由于尚不清楚用于RG改进的仪表作用的三叶草核心，因此我们决定将Schrodinger功能方法应用于此目的。事实证明，由于裸量规耦合很大，因此需要精确控制O（a/l）错误。我们通过使用固定L（以物理单位为单位）的模拟来处理此问题，并确定了三叶草核心作为裸机耦合的函数。4。 Physics运行迈向现实的三个风味QCD模拟的第一步，我们使用16^3x32晶格开始在L/A = 2GEV下运行。我们计划执行浅色火锅频谱运行，然后确定光夸克质量和QCD耦合常数。关于重夸克物理学的进一步工作应利用这些研究中产生的量规配置。较少的