1992 Fiscal Year Final Research Report Summary
| Project/Area Number |
03640270
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
核・宇宙線・素粒子
|
|---|
| Research Institution | KYOTO UNIVERSITY |
|---|
Principal Investigator |
FUKUGITA Masataka Kyoto University Yukawa Institute Associate Professor, 基礎物理学研究所, 助教授 (40100820)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
UKAWA Akira University of Tsukuba Institute of Physics Professor, 物理学系, 教授 (10143538)
|
|---|
| Project Period (FY) |
1991 – 1992
|
| Keywords | lattice gauge theory / quantum chromodynamics / hadron spectroscopy / finite-size effect / numerical simulation / weak matrix elements |
|---|
| Research Abstract |
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).
|
