| Project/Area Number |
07640375
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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 |
YOSHIE Tomoteru Center for computational Physics, University of Tsukuba AP, 物理学系・計算物理学研究センター, 講師 (40183991)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | QCD / finite temperature / simulation / strange quark / chiral transition / string tension / scaling / improved action / simula,tion / stranep quark / scaling / 有限温度QCD / 改良された作用 / 格子量子色力学 / カイラル相転移 / スケーリング則 |
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| Research Abstract |
Finite temperature transition in lattice QCD is numerically investigated, using a renormalization group (RG) improved gauge action and the standard Wilson quark action.
(a) Scaling property of the ratio of the critical temperature T_c to the square root of the string tension sigma in pure gauge theory is much improved for the RG improved action : The values of T_c/*sigma are identical within errors for N_t=3,4 and 6 lattices. The value of T_c in the continuum limit is about 276 MeV,which is slightly larger than that obtained for the standard action.
(b) We find the followings for N_F=2QCD.
i.The transition is smooth for a wide range of the quark mass. The unexpected sharp transition observed with the standard action is a lattice artifact.
ii.Pion screening mass on the critical line together with that on the transition line decrease smoothly to zero toward the chiral transition point. This implies that the chiral transition is continuous.
iii.Chiral condensation satisfies the scaling relation with critical exponents of the three dimensional O (3) spin model. This property strongly suggests that the chiral transition is of second order.
We also investigate the phase structure of QCD for general number of flavors with the standard Wilson quarks, varing N_F from 2up to 300. we proposed the following phase structure.
(a) For N_F <greater than or equal> 17, there is only a trivial fixed poin
(b) For 16 <greater than or equal> N_F <greater than or equal> 7, the theory is non-trivial without quark c
(c) For N_F <less than or equal> 6, the theory is non-trivial with both quark confinement and spontaneous chiral symmetry breaking at zero temperature.
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