NUMERICAL STUDY OF LATTICE QUANTUM CHROMODYNAMICS

晶格量子色动力学的数值研究

基本信息

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

项目摘要

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晶格QCD中的一个重要课题，因为它可能对整个粒子标准模型的研究产生影响。该项目旨在提取足够精确的介子弱相互作用矩阵元，以用于现象学。 (1) 淬火QCD中K介子B参数的精密测量Kogut-Susskind 和 Wilson 夸克作用。对于 Kogut-Susskind 夸克作用，使用两种类型的晶格算子对 0.24fm 至 0.041fm 范围内的七个晶格间距测量矩阵元素，得出值 B_K (2GeV,NDR) = 0.628 (42).对于威尔逊夸克作用，基于手征沃德恒等式的方法已经被开发和应用对 4 个晶格间距值进行模拟，得出 B_K (2GeV,NDR) =0.62 (10)。两种类型的离子的值显示出很好的一致性。我们的值代表了获得的最佳值。 (2) 淬灭 QCD 中 B 介子衰变常数的精确测量这个量的困难源于与 b 夸克的重质量相关的误差。在这个项目中，一组平行的夸克。已经进行了模拟，一个使用威尔逊夸克作用，另一个使用三叶草作用，预计可以减少尺度破坏效应的大小，并调用 El-Khadra-Kronfeld-Mackenzie 方法进行模拟。为了估计与 b 夸克相关的系统误差，我们获得了以下衰减常数值作为我们的最佳估计： 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) 弱衰变的形状因子我们还检验了计算半轻子弱衰变形状因子的可行性。我们的研究表明，形状因子显着取决于介子质量，并且统计信号。对于非零动量，这些点的进一步检查和新技术的开发似乎需要该领域的真正进展。上述结果已作为 K 介子的 B 参数和衰变常数的年度莱迪思会议系列报告。 B介子，我们的模拟已经在本财年准备并提交了。