权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

数値的方法に拠る量子色力学の研究

利用数值方法研究量子色动力学

基本信息

批准号：
03640270
负责人：
FUKUGITA Masataka
金额：
$ 1.41万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Spectroscopic problems of lattice QCD is studied by numerical methods. The main results are(1) Unexpectedly large finite-size effects are found in hadron spectrum calculations for full QCD. This means that a proper control is necessary over the finite lattice effect to calculate the hadron mass with an accuracy of a few %. We also found that this finite-size effect is described by a power law rather than exponential as expected in field-theoretical considerations. We ascribe its origin to a real-size of hadrons confined in a finite box.(2) The validity is examined for the perturbative prescription in extracting weak matrix elements from lattice calculations, which has been often cast a doublet. We found, at least for the case of the pion-decay matrix element and the K^0 - K^0 mixing matrix element, that the prescription is justifiable.(3) The choice of hadron operators in lattice calculation of hadron spectrum is not unique, and there is a suspicion that this may cause uncertainties in calculated hadron masses. A study on this problem is made in a systematic way and it was shown that there indeed is a significant uncertainty associated with the choice of hadron operators. We have just clarified the presence of the problem. The solution is yet to be found.(4) A new technique is developed which makes it possible to calculate the pion scattering length for all possible pipi channels. (In the past only the I = 2 amplitude was calculated).

用数值方法研究了晶格QCD的光谱问题。主要结果有：(1)在全QCD的强子谱计算中发现了出乎意料的大有限尺寸效应。这意味着，要使强子质量的计算精度达到几个百分点，必须对有限晶格效应进行适当的控制。我们还发现，这种有限大小的效应是用幂律来描述的，而不是像现场理论考虑中预期的那样是指数的。我们把它的起源归因于一个实际大小的强子被限制在一个有限的盒子里。(2)验证了从晶格计算中提取弱矩阵元素的微扰处方的有效性，这种方法通常是双重的。我们发现，至少对于介子衰变矩阵元素和K^0 - K^0混合矩阵元素的情况，这个公式是合理的。(3)强子谱点阵计算中强子算子的选择并不是唯一的，这可能会导致计算出的强子质量存在不确定性。对这一问题进行了系统的研究，结果表明，强子算子的选择确实存在很大的不确定性。我们刚刚澄清了问题的存在。解决方案尚未找到。(4)提出了一种计算所有可能π π通道的π介子散射长度的新方法。（过去只计算I = 2振幅）。