Study of the origin of the nucleon mass via photo-production of eta-prime meson

• Project/Area Number: 16H06007
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Kyoto Sangyo University (2017-2020); Kyoto University (2016)
• Principal Investigator: NIIYAMA Masayuki 京都産業大学, 理学部, 准教授 (90455361)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥21,840,000 (Direct Cost: ¥16,800,000、Indirect Cost: ¥5,040,000); Fiscal Year 2019: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2017: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2016: ¥16,120,000 (Direct Cost: ¥12,400,000、Indirect Cost: ¥3,720,000)
• Keywords: 核中のハドロンの性質 / 原子核物理 / ハドロン物理 / 質量の起源 / 放射線検出器 / 実験核物理

Outline of Final Research Achievements

The mass of material is the mass of nucleons in the nucleus, and theoretically explained that its origin is the quark condensation due to the strong interaction between quarks. According to recent theoretical study, the quark condensation reduces in the nucleus, and the mass of eta-prime meson become much lighter than that in the vacuum, which results in the formation of eta-prime bound nucleus. We searched for the eta-prime nucleus using the gamma ray beam at SPring-8. We did not observe the signal of eta-prime nucleus, and the interaction between a eta-prime meson and a nucleus is not strong as expected. We published this results in the physics journal.

Academic Significance and Societal Importance of the Research Achievements

本研究の成果の１つとして大面積の高時間分解能検出器の開発が挙げられます。この検出器は素粒子・原子核の様々な実験で利用できます。さらに、ミューオン透視などの素粒子・原子核分野以外の幅広い分野での応用が期待できます。
本研究によってη′中間子の質量が原子核中で非常に軽くなる可能性は低い事が分かりました。この結果から原子核中のη′中間子の質量がどのようにして生成されているのか、また原子核中のクォーク凝縮量との関係について理論模型に制限をかけ、より正確に理解できるようになりました。これは、身の回りの物質の質量の起源を理解する上で重要な情報になると考えています。

Research Products

• [Int'l Joint Research] Ohio university(米国)
• [Int'l Joint Research] Korea university(韓国)
• [Int'l Joint Research] 欧州原子核研究機構(スイス)
• [Journal Article] Search for η′ Bound Nuclei in the C12(γ,p) Reaction with Simultaneous Detection of Decay Products (2020)
  • Author(s): N.Tomida, N.Muramatsu, M.Niiyama, J.K.Ahn, W.C.Chang, J.Y.Chen, M.L.Chu, S.Date, T.Gogami, H.Goto, H.Hamano, T.Hashimoto, Q.H.He, K.Hicks, T.Hiraiwa, Y.Honda, T.Hotta, H.Ikuno, Y.Inoue, T.Ishikawa, I.Jaegle, J.M.Jo, Y.Kasamatsu, H.Katsuragawa, S.Kido, Y.Kon, T.Maruyama, (全63名）
  • Journal Title: Physical Review Letters Volume: 124 Issue: 20 Pages: 202501-202501
  • DOI: 10.1103/physrevlett.124.202501
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] A compensated multi-gap RPC with 2 m strips for the LEPS2 experiment (2019)
  • Author(s): Watanabe K.、Tanaka S.、Chang W.C.、Chen H.、Chu M.L.、Cuenca-Garcia J.J.、Gogami T.、Gonzalez-Diaz D.、Niiyama M.、Ohashi Y.、Ohnishi H.、Tomida N.、Yosoi M.
  • Journal Title: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 925 Pages: 188-192
  • DOI: 10.1016/j.nima.2019.02.014
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Status and Prospects of LEPS2 Solenoid Spectrometer (2017)
  • Author(s): M. Niiyama
  • Journal Title: JPS Conference Proceedings Volume: 13
  • DOI: 10.7566/jpscp.13.020009
  • Peer Reviewed / Open Access
• [Presentation] Recent results of few body system in the hadron physics with photon beam (2021)
  • Author(s): M. Niiyama
  • Organizer: The 8th Asia-Pacific Conference on Few-Body Problems in Physics
  • Int'l Joint Research / Invited
• [Presentation] LEPS2/BGOegg実験におけるη'中間子束縛核探索の実験結果 (2020)
  • Author(s): 冨田夏希
  • Organizer: 日本物理学会 第75回年次大会
• [Presentation] Hadron physics with photon beam (2019)
  • Author(s): Masayuki Niiyama
  • Organizer: The 3rd J-PARC Symposium
  • Int'l Joint Research / Invited
• [Presentation] LEPS2実験におけるBarrel RPC ToF system の性能評価Ⅰ (2019)
  • Author(s): 渡邊憲
  • Organizer: 日本物理学会 2019年秋季大会
• [Presentation] LEPS2用TPCの性能評価Ⅱ (2019)
  • Author(s): 小早川亮
  • Organizer: 日本物理学会 2019年秋季大会
• [Presentation] Recent results and prospects from Belle I, Belle II and LEPS 1, LEPS 2 (2018)
  • Author(s): M. Niiyama
  • Organizer: 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Int'l Joint Research / Invited
• [Presentation] The Development of 2 m long multigap RPCs for LEPS2 experiment (2018)
  • Author(s): K. Watanabe, M. Niiyama, S. Tanaka, M. Yosoi
  • Organizer: 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Int'l Joint Research
• [Presentation] Performance evaluation of Time Projection Chamber for LEPS2/SPring-8 (2018)
  • Author(s): R. Kobayakawa, M. Niiyama, , M. Yosoi, S. Ajimura, S. Y. Ryu, Y. Sada, K. Mizutani
  • Organizer: 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Int'l Joint Research
• [Presentation] η photo-production from proton target at LEPS2/BGOegg experiment (1) (2017)
  • Author(s): T. H. Nam
  • Organizer: 日本物理学会 第72回年次大会
  • Place of Presentation: 大阪大学
  • Year and Date: 2017-03-17
• [Presentation] LEPS2/BGOegg 実験における液体水素標的 を用いたη中間子光生成反応(2) (2017)
  • Author(s): 橋本敏和
  • Organizer: 日本物理学会 第72回年次大会
  • Place of Presentation: 大阪大学
  • Year and Date: 2017-03-17
• [Presentation] LEPS2 実験でのトリガースタデ ィと e+e－ 除去用検出器の作成 (2017)
  • Author(s): 渡邊 憲
  • Organizer: 日本物理学会 第72回年次大会
  • Place of Presentation: 大阪大学
  • Year and Date: 2017-03-17
• [Presentation] LEPS2実験に用いる TIME PROJECTION CHAMBER(TPC) の性能評価 (2017)
  • Author(s): 小早川 亮
  • Organizer: 日本物理学会 第72回年次大会
  • Place of Presentation: 大阪大学
  • Year and Date: 2017-03-17
• [Presentation] Status and Prospects of LEPS2 Solenoid Spectrometer (2016)
  • Author(s): 新山 雅之
  • Organizer: The 14th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon
  • Place of Presentation: Kyoto, Japan
  • Year and Date: 2016-07-25
  • Int'l Joint Research
• [Remarks] -高輝度γ線を用いたハドロン物理-
  • URL: http://www-nh.scphys.kyoto-u.ac.jp/Activity/spring8-j.html
• [Remarks] SPring-8 での研究活動
  • URL: http://www.rcnp.osaka-u.ac.jp/~niiyama/sp8/