| Project/Area Number |
18K03605
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2021: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
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| Keywords | ハドロン / 量子色力学 / 格子ゲージ理論 / 核子構造 / 陽子サイズのパズル / 中性子寿命のパズル / 陽子スピンのパズル |
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| Outline of Final Research Achievements |
In this study, realistic lattice QCD calculations, where three dynamical quark degrees of freedom (up, down, and strange) are treated rigorously with physical quark masses, have been performed for nucleon form factors, which should include information of the nucleon structure, with the statistical errors at a few % level. Accurate theoretical evaluation of the nucleon form factors is a gateway to a comprehensive understanding of the internal structure of nucleons and is expected to provide clues to the full clarification of various unsolved problems discussed in the experimental field. Using lattice QCD simulations only at the physical point, we have succeeded in reproducing the experimental values of the nucleon axial charge, which is one of the most important pieces of information on the nucleon structure, with an error of less than 2%, ahead of other studies in the world.
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| Academic Significance and Societal Importance of the Research Achievements |
現在、格子QCD計算は、強い相互作用の第一原理計算により、陽子や中性子（２つ合わせて核子）の質量を誤差1%レベルで実験値を再現できている精密理論計算として知られているが、核子の構造に関して、同様の精密計算を達成できると、実験分野で議論されている「陽子半径パズル」に代表される核子構造におけるいくつかの未解決問題に対して、その全容解明に貢献できる。本研究では、核子構造の情報の一つである、核子軸性電荷に対して誤差2%以下の精度の精密理論計算を達成させ、今後、陽子半径を含む核子構造に関係する基本的な物理量に対して、誤差数%レベルの精密理論計算が実現可能なことを示した。
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