| Project/Area Number |
17540259
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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 |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Hiroshima University |
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Principal Investigator |
OKAWA Masanori Hiroshima University, Graduate School of Science, Professor (00168874)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,730,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Lattice QCD / Dynamical quark / 3 flavor |
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| Research Abstract |
The purpose of the present study is to make lattice QCD simulations including dynamical effects of 3 flavor (u,d,s) quarks and to verify that 3 flavor QCD, can correctly reproduce physical properties of the real world.
1) We made the realistic 3 flavor QCD simulations with the O(α) improved Wilson fermion in which the discretization error of lattice QCD simulations is known to be O(α^2) with α the lattice spacing. We calculated physical quantities on three lattices having the squared lattice spacings α^2〓 0.005, 0.01 and 0.015 fm^2 , and extrapolated physical quantities to α= 0 assuming α^2 scaling. We found that the meson masses are consistent with experimental values within errors of about 1% level, and that the values of quark masses turn out to be smaller than the values of quark masses usually used in phenomenological studies.
2) The computational cost of lattice QCD simulations is inversely proportional to the third power of quark masses. Since the u and d quark masses are very small being about 5MeV, it is difficult to take into account the dynamical quark effects of the realistic light quark masses. In the above study 1), we have made the simulations with the dynamical u,d quark masses in the range of 50MeV-120MeV, and estimated the values of physical quantities at the realistic quark masses by extrapolation in quark masses. To make simulations with smaller quark masses, we improved our simulation algorithm. We then made the simulations with the dynamical u,d quark masses in the range of 10MeV-50MeV and succeeded in reducing the systematic error coming from the extrapolation in quark masses.
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