NUMERICAL STUDY OF LATTICE QCD WITH THREE DYNAMICAL QUARKS

三动态夸克晶格QCD的数值研究

• 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

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

本工作的目的是发展格点QCD模拟的方法，包括动力学奇异夸克和动力学上、下夸克。主要结果如下：1.算法开发处理奇数个动力学夸克需要算法开发。我们已经表明，多项式HMC，其中所需的奇异夸克的一个狄拉克算子的逆近似的多项式，为此目的提供了一个可行的方法。我们还将该算法推广到Kogut-Susskind作用量，并给出了一个精确的PHMC算法，这种精确的算法以前是未知的.三味格点QCD的相结构我们应用该算法研究了有限格点间距下三味格点QCD的相结构。结果发现，结合的元格和三叶草夸克作用发展的一级相变线，这是一个晶格的假象。而转换在 ...更多信息 当达到连续极限时，终止点的晶格间距约为4GeV。由于我们需要开始模拟更接近连续极限，以避免这种相变的非物理效应，因此斑片-三叶草组合对于进行实际模拟来说似乎是不切实际的。将规范作用量切换到RG改进作用量，发现相变消失，推测是因为规范场涨落在改进作用量下变得更像连续场.确定RG改进规范作用量的三叶草系数为了用晶格间距1/a=1-2GeV进行连续外推，需要O（a）改进作用量。由于RG改进规范作用的三叶草系数未知，我们决定为此目的应用薛定谔泛函方法。事实证明，为此目的需要精确控制O（a/L）误差，因为裸规耦合很大。我们通过固定L（物理单位）的模拟来处理这个问题，并确定了三叶草系数作为裸规范耦合的函数.物理运行作为实现现实的三味QCD模拟的第一步，我们已经开始使用16^3x32晶格在l/a=2GeV运行。我们计划进行轻强子谱运行，然后确定轻夸克质量和QCD耦合常数。关于重夸克物理学的进一步工作将利用这些研究中产生的规范组态。少

项目成果

S.Aoki et al.: "Non-Perturbative Determination of c_SW in Three-flavor Dynamical QCD"Nucl.Phys.B (Proc. Suppl.). (to appear).

S.Aoki 等人：“三味动态 QCD 中 c_SW 的非微扰测定”Nucl.Phys.B（Proc. Suppl.）。

S. Aoki, R. Burkhalter, M. Fukugita, S, Hashimoto, K-I. Ishikawa, N. Ishizuka, Y., Iwasaki, K. Kanaya, T. Kaneko, Y. Kuramashi, M. Okawa, T. Onogi, S. Tominaga, N. Tsutsui, A. Ukawa, N.,Yamada, T. Yoshie: "Non-trivial phase structure of N_f=3 QCD with O(a

S. Aoki、R. Burkhalter、M. Fukugita、S、Hashimoto、K-I。

S. Aoki, M. Fukugita, S. Hashimoto, K-I. Ishikawa, N. Ishizuka, Y. Iwasaki, K, Kanaya, T. Kaneko, Y. Kuramashi, M. Okawa, N. Tsutsui, A. Ukawa, N. Yamada, T. Yoshie: "An Exact Algorithm for Anyflavor Lattice QCD with Kogut-Susskind Fermion"submitted to Co

S.青木，M.福吉塔，S.桥本，K-I。

S.Aoki et al.: "Non-trivial phase structure of N_f=3 QCD with O(a)-improved Wilson fermion at zero temperature"Nucl.Phys.B (Proc. Suppl.). 106. 263-265 (2002)

S.Aoki 等人：“零温下具有 O(a) 改进的威尔逊费米子的 N_f=3 QCD 的非平凡相结构”Nucl.Phys.B（Proc. Suppl.）。

S. Aoki, R, Burkhalter, M. Fukugita, S. Hashimoto, K-I. Ishikawa, N. Ishizuka, Y., Iwasaki, K. Kanaya, T. Kaneko, Y. Kuramashi, M. Okawa, T. Onogi, S. Tominaga, N. Tsutsui, A. Ukawa, N., Yamada, T. Yoshie: "An exact algorithm for three-flavor QCD with 0(a

S. Aoki, R、Burkhalter、M. Fukugita、S. Hashimoto, K-I。