NUMERICAL STUDY OF LATTICE QUANTUM CHROMODYNAMICS

晶格量子色动力学的数值研究

• 批准号: 08640349
• 负责人: UKAWA Akira
• 金额: $ 1.09万
• 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: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640349/
• 关键词: PARTCLE PHYSICS; STRONG INTERACTIONS; LATTICE QCD; NUMERICAL SIMULATION; WEAK INTERACTION; CP VIOLATION; CKM MATRIX; B MESON

Study of weak interation matrix elements of hadrons is an important subject in lattice QCD in view of its possible impact on research of the Standard Model of particles as a whole. This project aimed to extract weak matrix elements of mesons, sufficiently accurate for use in phenomenological analyzes, through systematic large scale numerical simulation of lattice QCD.The main results of the project are as follows.(1) Precision measurement of K meson B parameter in quenched QCDSimulations have been made both for the Kogut-Susskind and Wilson quark actions.For the Kogut-Susskind quark action, the matrix element was measured using two types of lattice operators for seven lattice spacings ranging over 0.24fm to 0.041fm, which yielded the value B_K (2GeV,NDR) =0.628 (42).For the Wilson quark action, the method based on chiral Ward identities have been developed and applied to simulations for 4 values of lattice spacing, yielding B_K (2GeV,NDR) =0.62 (10).The values from the two types of act … More ions show a good agreement. Our values represent the best result obtained so far for this important quantity.(2) Precision measurement of the B meson decay constant in quenched QCDThe difficulty with this quantity stems from systematic errors associated with heavy mass of the b quark. In this project, a parallel set of simulations have been carried out, one using the Wilson quark action and the other employing the clover action which is expected to have reduced magnitude of scaling violation effects. Carrying out simulations for 3 lattice spacings and invoking the method of El-Khadra-Kronfeld-Mackenzie for estimating systematic errors associated with b quark, we have obtained the following values for the decay constant as our best estimate : f_B=173 (5) (9) (14) MeV,f_<Bs>=199 (3) (10) (16) MeV,f_D=197 (3) (14) (17) MeV,f_<Ds>=224 (3) (16) (18) MeV.(3) Form factors for weak decaysWe have also examined the feasibility of calculating semi-leptonic weak decay form factors. Our study shows that the form factor depends significantly on the meson mass, and that statistical signals deteriorate rapidly for non-zero momenta. Further check of these points and development of a new technique appear needed for real progress in this area.Results above have been reported as annual Lattice conference series. For the B parameter of K meson and the decay constant of B meson, our simulations have been completed. Journal articles have been prepared and submitted in this fiscal year. Less

强子弱相互作用矩阵元的研究是格点QCD的一个重要课题，因为它可能对整个粒子标准模型的研究产生影响。本项目旨在通过对格点QCD的系统的大尺度数值模拟，提取出足够精确的介子弱矩阵元，以用于唯象分析。(1)本文对Kogut-Susskind夸克作用量和Wilson夸克作用量进行了猝灭QCD模拟中K介子B参数的精确测量。对于Kogut-Susskind夸克作用量，在0.24 ~ 0.041 fm的七个格点间距范围内，用两种格点算符测量了矩阵元，得到了B_K值（2GeV，NDR）=0.628（42）.对于Wilson夸克作用量，我们发展了基于手征Ward恒等式的方法，并对4种格点间距进行了模拟，得到B_K（2GeV，NDR）=0.62（10）. ...更多信息 离子显示出良好的一致性。我们的值代表了迄今为止对这一重要量所获得的最佳结果。(2)猝灭QCD中B介子衰变常数的精确测量这个量的困难来自与B夸克的重质量有关的系统误差。在这个项目中，已经进行了一组平行的模拟，一个使用威尔逊夸克作用，另一个采用三叶草作用，预计将有规模的标度破坏效应的减少。对3种格点间距进行模拟，并引用El-Khadra-Kronal-Mackenzie方法估计与B夸克有关的系统误差，得到了衰变常数的最佳估计值：f_B=173（5）（9）（14）MeV，f_D <Bs>=199（3）（10）（16）MeV，f_D=197（3）（14）（17）MeV，f_<Ds>D =224（3）（16）（18）MeV。(3)我们还研究了计算半轻子弱衰变形状因子的可行性。我们的研究表明，形状因子依赖于介子质量显着，统计信号迅速恶化的非零动量。为了在这一领域取得真实的进展，需要进一步检查这些点并开发一种新技术。对于K介子的B参数和B介子的衰变常数，我们完成了模拟。本财政年度已编写并提交期刊文章。少

项目成果

S.Aoki et al: "K^+→Π^+Π^○ docay amplitude in guenched lettice QCD" Nul.Phys.B(Proc.Suppl.). 63. 284-286 (1998)

S.Aoki 等人：“K^+→Π^+Π^○ gunched lettice QCD 中的 docay 振幅”Nul.Phys.B(Proc.Suppl.) 63. 284-286 (1998)。

JLQCD Collaboration (S.Aoki et al.): "B_K with the Wilson quark action : a non-perturbative resolution of operator mixing using chiral Ward identities" Nuclear Physics B (Proc.Suppl.). 53. 349-354 (1997)

JLQCD 协作（S.Aoki 等人）：“B_K 与威尔逊夸克作用：使用手性 Ward 恒等式算子混合的非微扰分辨率”核物理 B（Proc.Suppl.）。

JLQCD Collaboration (S.Aoki et al.): "Toward the continuum limit of B_K with the quenched Kogut-Susskind quark action" Nuclear Physics B (Proc.Suppl.). 53. 341-344 (1997)

JLQCD 协作（S.Aoki 等人）：“通过淬灭的 Kogut-Susskind 夸克作用实现 B_K 的连续极限”核物理 B（Proc.Suppl.）。

JLQCD Collaboration (S.Aoki et al.): "Continuum limit of the heavy-light decay constant with the quenched Wilson quark action" Nuclear Physics B (Proc.Suppl.). 53. 355-357 (1997)

JLQCD 合作（S.Aoki 等人）：“具有猝灭威尔逊夸克作用的重光衰变常数的连续极限”核物理 B（Proc.Suppl.）。

JLQCD Collaboration (S.Aoki et al.): "K^+ ->pi^0+pi^+ decay amplitude in quenched lattice QCD" Nuclear Physics B (Proc.Suppl.). 63. 284-286 (1998)

JLQCD 协作（S.Aoki 等人）：“K^ ->pi^0 pi^ 淬灭晶格 QCD 中的衰变幅度”核物理 B（Proc.Suppl.）。