2002 Fiscal Year Final Research Report Summary
NUMERICAL STUDY OF LATTICE QCD WITH THREE DYNAMICAL QUARKS
| Project/Area Number |
13640259
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | UNIVERSITY OF TSUKUBA |
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Principal Investigator |
UKAWA Akira INSTITUTE OF PHYSICS PROFESSOR, 物理学系・(計算物理学研究センター), 教授 (10143538)
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| Project Period (FY) |
2001 – 2002
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| Keywords | LATTICE GAUGE THEORY / LATTICE QCD / NUMERICAL SIMULATIONS / QUARK / PHASE TRANSITION / CLOVER ACTION / MONTE CARLO METHOD / PERTURBATIVE EXPANSION |
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| Research Abstract |
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 development
Treating 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 QCD
We 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 action
To 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 runs
As 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
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Research Products
(12 results)
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[Publications] S. Aoki, M. Fukugita, S. Hashimoto, K-I. Ishikawa, N. Ishizuka, Y. Iwasaki, K. Kanaya, T. Kaneko, Y. Kuramashi, M. Okawa, V. Lesk, Y. Taniguchi, N. Tsutsui, A. Ukawa, T, Umeda, N, Yamada, T, Yoshie: "Non-Perturbative Determination of c_SW in Three-flavor Dynamical QCD"Lattice2002(Improvement and Renormalization), in the proceedings. to appear. (2002)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Y. Namekawa, S. Aoki, M. Fukugita, K-I. Ishikawa, N. Ishizuka, Y. Iwasaki, K, Kanaya, T. Kaneko, Y. Kuramashi, V.I. Lesk, M. Okawa, Y. Taniguchi, A. Ukawa, T. Umeda, T. Yoshie: "Exploring QCD at small sea quark masses with improved Wilson-type quarks"to appear. (2002)
Description
「研究成果報告書概要(欧文)」より
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[Publications] K-I. Ishikawa, M. Fukugita, S. Hashimoto, N. Ishizuka, Y. Iwasaki, K. Kanaya, Y. Kuramashi, M. Okawa, N. Tsutsui, A. Ukawa, N. Yamada, T. Yoshie: "An exact Polynomial Hybrid Monte Carlo algorithm for dynamical Kogut-Susskind fermions"Lattice2002(algor), in the proceedings. to appear. (2002)
Description
「研究成果報告書概要(欧文)」より
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[Publications] 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 Computer Physics Communications.
Description
「研究成果報告書概要(欧文)」より
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[Publications] 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: "Polynomial Hybrid Monte Carlo algorithm for lattice QCD with an odd number of flavors"Phys.Rev. D. 65. 094507 (2002)
Description
「研究成果報告書概要(欧文)」より
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[Publications] 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)-improved Wilson fermions"Nucl. Phys. Proc. Suppl.. 106. 1079-1081 (2002)
Description
「研究成果報告書概要(欧文)」より
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[Publications] 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)-improved Wilson fermibn at zero temperature"Nucl. Phys. Proc. Suppl.. 106. 263-265 (2002)
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「研究成果報告書概要(欧文)」より
