Charge symmetry breaking from the neutron-neutron scattering length determined by using virtual photons

• Project Area: Toward new frontiers : Encounter and synergy of state-of-the-art astronomical detectors and exotic quantum beams
• Project/Area Number: 19H05181
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: Tohoku University
• Principal Investigator: 石川 貴嗣 東北大学, 電子光理学研究センター, 助教 (40400220)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2020: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000); Fiscal Year 2019: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
• Keywords: 荷電対称性の破れ / 核力 / バリオン・バリオン相互作用

Outline of Research at the Start

本研究では電子非弾性散乱(e,e')の仮想光子γ*を用いたγ*d→π+nn反応でγ*の方向に放出されるπ+ので運動量を精度良く測定することで中性子どうしの相互作用の散乱長を決定する。超高分解能磁気スペクトロメータを 3 つ保有し、電子、π+の散乱角、運動量を高分解能で測定できるドイツ MAMI 施設で実験を行い、電磁相互作用の効果を補正した陽子どうしの散乱長と比較することで荷電対称性の破れを定量的に議論し、荷電対称性の破れの起源を解明することを目指す。

Outline of Annual Research Achievements

「荷電対称性」は強い相互作用がもつ基本的な対称性であり、陽子 (p) と中性子 (n) を入れ替えても核力や原子核の性質は基本的に変わらない、とされてきた。素過程で考えると荷電対称性は u クォークとd クォークの入れ替えに対する対称性であり、その破れの度合いは高々 u クォークとd クォークの質量差、電磁相互作用の効果の違い程度である。ところがいまΛバリオンを含む原子核の質量から、これらでは説明できない大きな荷電対称性の破れ、すなわちΛp 間とΛn間の相互作用の違い、が提唱されている。核子どうしの散乱の場合でも、アイソスピン 1 が保証される pp 散乱と nn 散乱の散乱長は電磁相互作用の効果を補正すると -17.3±0.4 fm、-18.9± 0.4 fm であり、これらの差はクォークの質量差で説明がつく 0.3 fm よりずっと大きくなっているように見える。これまでの nn 散乱長の決定方法には問題があり、本当に pp と nn で散乱長が異なっているのか定かではない。そこで本研究では、nn 散乱の散乱長を精密に決定し、電磁相互作用の効果を補正したppの散乱長と比較する。これにより荷電対称性の破れを定量的に議論し、破れの起源を解明することを目指す。直接nn散乱実験を行うことがほぼ不可能であるためnnの散乱長の決定は間接的なものにならざるを得ない。そこで電子非弾性散乱(e,e')の仮想光子γ*を用いたγ*d→π+nn反応のnn不変質量に対する微分断面積からnn散乱長を精密に決定する。この手法が可能であることを理論的な考察で示し、まとめた学術論文を Physical Review C 誌に投稿した (arXiv:2003.0249)。また Mainz MAMI 施設での電子散乱実験での最適な運動学を評価し、国際セミナー「Joint THEIA-STRONG2020 and JAEA/Mainz REIMEI Web-Seminar」で紹介した。

Research Progress Status

令和2年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和2年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Experimental study of (p, 2p) reactions at 392 MeV on 12C, 16O, 40Ca and 208Pb nuclei leading to low-lying states of residual nuclei (2020)
  • Author(s): Tetsuo Noro, Takatsugu Ishikawa et al.
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: 2020 Issue: 9
  • DOI: 10.1093/ptep/ptaa109
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Differential cross sections, photon beam asymmetries, and spin density matrix elements of ω photoproduction off the proton at Eγ=1.3?2.4 GeV (2020)
  • Author(s): Muramatsu N. et al. LEPS2/BGOegg Collaboration
  • Journal Title: Physical Review C Volume: 102 Issue: 2 Pages: 025201-025201
  • DOI: 10.1103/physrevc.102.025201
  • Peer Reviewed / Int'l Joint Research
• [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] ωN scattering length from ω photoproduction on the proton near the reaction threshold (2020)
  • Author(s): Ishikawa T.、7番目
  • Journal Title: Physical Review C Volume: 101 Issue: 5 Pages: 052201-052201
  • DOI: 10.1103/physrevc.101.052201
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Non-strange dibaryons studied in coherent double neutral-meson photoproduction on the deuteron (2020)
  • Author(s): Takatsugu Ishikawa et al.
  • Journal Title: EPJ Web of Conferences Volume: 241 Pages: 01007-01007
  • DOI: 10.1051/epjconf/202024101007
  • Peer Reviewed / Open Access
• [Journal Article] ωN scattering length from ω photoproduction on the proton near the threshold (2020)
  • Author(s): Takatsugu Ishikawa et al.
  • Journal Title: AIP Conference Proceedings Volume: 2249 Pages: 030027-030027
  • DOI: 10.1063/5.0008651
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] ωN scattering length from ω photoproduction on the proton near the threshold (2020)
  • Author(s): T. Ishikawa et al.
  • Journal Title: AIP Conference Proceedings Volume: 2319 Pages: 080017-080017
  • DOI: 10.1063/5.0036979
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Neutron-neutron scattering length from π+ photoproduction on the deuteron (2020)
  • Author(s): S.X. Nakamura, T. Ishikawa, T. Sato
  • Journal Title: arXiv preprint Volume: nucl-th
  • Open Access
• [Journal Article] ηN Scattering Parameters and Possible η'd Bound State from η Photoproduction on the Deuteron (2020)
  • Author(s): T. Ishikawa et al.
  • Journal Title: Acta Physica Polonica B Volume: 51 Issue: 1 Pages: 27-32
  • DOI: 10.5506/aphyspolb.51.27
  • Peer Reviewed / Open Access
• [Journal Article] Non-strange dibaryons studied in coherent double neutral-meson photoproduction on the deuteron (2020)
  • Author(s): T. Ishikawa et al.
  • Journal Title: Acta Physica Polonica B Volume: 51 Issue: 1 Pages: 329-332
  • DOI: 10.5506/aphyspolb.51.329
  • Peer Reviewed / Open Access
• [Journal Article] Performance of the FOREST/BLC Spectrometer for Study of the η-nucleon Interaction via the γd→pηn Reaction (2020)
  • Author(s): S. Miyata, T. Ishikawa et al.
  • Journal Title: Springer Proceedings in Physics Volume: 238 Pages: 705-708
  • DOI: 10.1007/978-3-030-32357-8_113
  • ISBN: 9783030323561, 9783030323578
  • Peer Reviewed
• [Journal Article] Study of Non-strange Dibaryon Resonances Via Coherent Double Neutral-Meson Photoproduction from the Deuteron (2020)
  • Author(s): T. Ishikawa et al.
  • Journal Title: Springer Proceedings in Physics Volume: 238 Pages: 609-613
  • DOI: 10.1007/978-3-030-32357-8_96
  • ISBN: 9783030323561, 9783030323578
  • Peer Reviewed
• [Journal Article] 最近の研究から「光子ビームで探るクォーク・グルーオン多体系―ダイバリオンの発見から分光へ」 (2020)
  • Author(s): 石川貴嗣、笠木治郎太
  • Journal Title: 日本物理学会誌 BUTSURI Volume: 75
  • Peer Reviewed
• [Journal Article] Measuring Space-Time Properties of the Δ(1232) via Bose-Einstein Correlations (2019)
  • Author(s): Qinghua He, Takatsugu Ishikawa et al.
  • Journal Title: JPS Conference Proceedings Volume: 26
  • DOI: 10.7566/jpscp.26.024004
  • Peer Reviewed / Open Access
• [Journal Article] Non-strange Dibaryon Resonances Observed in Coherent Double Neutral-Pion Photoproduction on the Deuteron (2019)
  • Author(s): Takatsugu Ishikawa et al.
  • Journal Title: JPS Conference Proceedings Volume: 26
  • DOI: 10.7566/jpscp.26.022014
  • Peer Reviewed / Open Access
• [Journal Article] Experimental Study of Di-quark Correlation by CharmedBaryon Spectroscopy at J-PARC High-Momentum Secondary Beam Line (2019)
  • Author(s): Y. Komatsu
  • Journal Title: JPS Conf. Proc. Volume: - Pages: 022029-022029
  • DOI: 10.7566/jpscp.26.022029
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] eta photoproduction off the deuteron and low-energy eta-nucleon interaction (2019)
  • Author(s): S.X. Nakamura, H. Kamano, T. Ishikawa
  • Journal Title: JPS Conference Proceedings Volume: 26 Pages: 0230011-4
  • DOI: 10.7566/jpscp.26.023001
  • Peer Reviewed / Open Access
• [Presentation] Coherent neutral pion and eta meson photoproduction on the deuteron (2021)
  • Author(s): Takatsugu Ishikawa
  • Organizer: Yamada Conference LXXII: The 8th Asia-Pacific conference on Few-Body problems in Physics (APFB2020)
  • Int'l Joint Research
• [Presentation] ηd threshold structure from the γd→π0ηd reaction (2021)
  • Author(s): Takatsugu Ishikawa
  • Organizer: Hadron in Nucleus 2020 (HIN20)
  • Int'l Joint Research
• [Presentation] Hadron physics from meson photoproduction experiments at ELPH (2021)
  • Author(s): Takatsugu Ishikawa
  • Organizer: 東京工業大学量子物理学ナノサイエンス第307 回セミナー
  • Invited
• [Presentation] nn scattering length from positive pion photoproduction on the deuteron (2021)
  • Author(s): Takatsugu Ishikawa
  • Organizer: 東京工業大学インフォーマルセミナー
  • Invited
• [Presentation] Low-energy neutron-neutron scattering studied with pion photoproduction on the deuteron (2021)
  • Author(s): Satoshi X Nakamura
  • Organizer: Hadron in Nucleus 2020 (HIN20)
  • Int'l Joint Research
• [Presentation] Hadron-hadron scattering length from meson photoproduction (2020)
  • Author(s): Takatsugu Ishikawa
  • Organizer: Joint THEIA-STRONG2020 and JAEA/Mainz REIMEI Web-Seminar
  • Int'l Joint Research / Invited
• [Presentation] Hadron-hadron scattering length from meson photoproduction (2020)
  • Author(s): 石川貴嗣
  • Organizer: ELPH workshop C029 “様々なフレーバー領域で探るクォーク・ハドロン多体系の分光と構造”
• [Presentation] 重水素標的におけるコヒーレントπ0η光生成反応によるηN散乱長の決定 (2020)
  • Author(s): 石川貴嗣
  • Organizer: 新学術領域研究「量子クラスターで読み解く物質の階層構造」 ワークショップ（第5回クラスター階層領域研究会）
• [Presentation] 仮想光子を使った nn 散乱長の精密測定による荷電対称性の破れの研究 (2020)
  • Author(s): 石川貴嗣
  • Organizer: 新学術領域研究「宇宙観測検出器と量子ビームの出会い。新たな応用への架け橋。」 ワークショップ（第2回領域全体会議）
• [Presentation] Determination of eta-nucleon scattering length from eta photoproduction on the deuteron (2020)
  • Author(s): 石川貴嗣
  • Organizer: 新学術領域研究「量子クラスターで読み解く物質の階層構造」 ワークショップ（第3回クラスター階層領域研究会）
• [Presentation] Neutron-neutron scattering length from π+ photoproduction on the deuteron (2020)
  • Author(s): 中村聡
  • Organizer: ELPH workshop C029 “様々なフレーバー領域で探るクォーク・ハドロン多体系の分光と構造”
  • Invited
• [Presentation] Photo-production of the eta-meson on the deuteron (2020)
  • Author(s): Takatsugu Ishikawa
  • Organizer: International Symposium on Clustering as a Window on the Hierarchical Structure of Quantum Systems (CLUSHIQ2020)
  • Int'l Joint Research
• [Presentation] Dibaryon photoproduction on the deuteron detecting two neutral pions and deuteron (2020)
  • Author(s): Takatsugu Ishikawa
  • Organizer: KEK/Tokai Internal workshop on “Physics of heavy-quark and exotic hadrons”
  • Int'l Joint Research / Invited
• [Presentation] Experimental study of a light exotic baryon with neutral meson photoproduction (2020)
  • Author(s): Yusuke Tsuchikawa
  • Organizer: KEK/Tokai Internal workshop on “Physics of heavy-quark and exotic hadrons”
  • Int'l Joint Research / Invited
• [Presentation] ωN scattering length from ω photoproduction on the proton near the threshold (2019)
  • Author(s): Takatsugu Ishikawa
  • Organizer: The 15th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, MENU2019
  • Int'l Joint Research
• [Presentation] Non-Strange Dibaryons studied in coherent double neutral-meson photoproduction on the deuteron (2019)
  • Author(s): Takatsugu Ishikawa
  • Organizer: The 12th Internal workshop on the Physics of Excited Nucleons (NSTAR2019)
  • Int'l Joint Research
• [Presentation] ηN scattering parameters and possible η'N bound state from η photoproduction on the deuteron (2019)
  • Author(s): Takatsugu Ishikawa
  • Organizer: 3rd Jagiellonian Symposium on Fundamental and Applied Subatomic Physics
  • Int'l Joint Research / Invited
• [Presentation] Non-strange dibaryons studied in coherent double neutral-meson photoproduction on the deuteron (2019)
  • Author(s): Takatsugu Ishikawa
  • Organizer: 3rd Jagiellonian Symposium on Fundamental and Applied Subatomic Physics
  • Int'l Joint Research
• [Presentation] ωN scattering length from ω photoproduction on the proton near the threshold (2019)
  • Author(s): Takatsugu Ishikawa
  • Organizer: The 14th Asia-Pacific Physics Conference 2019 (APPC2019)
  • Int'l Joint Research
• [Presentation] Study of charge symmetry breaking from the precise and accurate measurement of the nn scattering length using virtual photons (2019)
  • Author(s): 石川 貴嗣
  • Organizer: 新学術領域研究「宇宙観測検出器と量子ビームの出会い。新たな応用への架け橋。」 ワークショップ（第1回領域全体会議）
• [Presentation] コヒーレントなダブルメソン光生成反応で探るダイバリオン共鳴, (2019)
  • Author(s): 石川 貴嗣
  • Organizer: ELPH workshop C024 “ハドロン構造における多粒子相関”
• [Presentation] Dynamical coupled-channels approach to electroweak reactions on nucleon and deuteron (2019)
  • Author(s): 中村 聡
  • Organizer: ELPH workshop C024 “ハドロン構造における多粒子相関”
  • Invited
• [Presentation] Dynamical coupled-channels approach to electroweak reactions on nucleon and deuteron (2019)
  • Author(s): Satoshi X Nakamura
  • Organizer: The 15th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon, MENU2019
  • Int'l Joint Research / Invited
• [Remarks] 仮想光子を用いたnn 散乱長の決定
  • URL: http://www.lns.tohoku.ac.jp/hadron/mbr/ishikawa/j2020b.html
• [Remarks] 仮想光子を用いたnn 散乱長の決定
  • URL: http://www.lns.tohoku.ac.jp/hadron/mbr/ishikawa/j2019b.html