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Study of correlation between proton spin and quark momentum in the polarized Drell-Yan process

Research Project

Project/Area Number 19K14729
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
Research InstitutionInstitute of Physical and Chemical Research (2020-2021)
Yamagata University (2019)

Principal Investigator

Nukazuka Genki  国立研究開発法人理化学研究所, 仁科加速器科学研究センター, 理研BNLセンター研究員 (00824864)

Project Period (FY) 2019-04-01 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2020: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Keywords核子構造 / 高エネルギーQCD / 陽子スピンの起源 / ドレル・ヤン過程 / 偏極標的 / TMD-PDFs
Outline of Research at the Start

本研究は素粒子・原子核物理学の実験による研究で,陽子の構造をクォーク,グルーオンレベルで解明するためのものである。陽子が複合粒子であることは 1960 年代から認識されているが,素粒子であるクォーク,グルーオンによる具体的な構造は未解決のままである。本研究では CERN の COMPASS 国際共同研究による偏極ドレル・ヤン実験のデータを利用し,山形大学での試験的な解析結果もとにスーパーコンピュータを利用して収集した膨大なデータを解析から,陽子スピンとクォークの横方向運動量の相関を表す構造の一端を明らかにする。

Outline of Final Research Achievements

This is research on proton structure by using the so-called polarized Drell-Yan (DY) process obtained by COMPASS collaboration at CERN in 2015 and 2018. This research focused on the Sivers parton distribution function, which describes the transverse momentum distribution of unpolarized partons in a transversely polarized proton. In the data analysis, elimination of background events, selection of muon-antimuon pair (dimuon) produced by the DY process, polarization determination of the target protons, and so on were performed. After the processes, dimuon angular asymmetries were extracted. One of the asymmetries related to Sivers distribution was found to be about +0.05. The result agrees with the theoretical framework describing the 3-dimensional momentum structure of a proton.

Academic Significance and Societal Importance of the Research Achievements

陽子は最も身近な物質粒子の一つだが解明されていない謎がいくつも残されており,陽子スピン 1/2 の期限もその一つである。クォーク,グルーオンで陽子スピンは構成されるが,それぞれのスピンだけではなく軌道角運動量も寄与しうる。陽子構造の立体的な記述は軌道角運動量の理解に必要で,本研究による Sivers 非対称度の符号は運動量空間を 3 次元に拡張する理論的な枠組みによる予言を支持するものであった。すなわち,我々の陽子内のクォークの 3 次元的運度量の理解が正しいという大きな証拠が得られ,陽子構造の理解が大きく進歩したことを意味する。

Report

(4 results)
  • 2021 Annual Research Report   Final Research Report ( PDF )
  • 2020 Research-status Report
  • 2019 Research-status Report
  • Research Products

    (10 results)

All 2022 2021 2020 2019 Other

All Int'l Joint Research (3 results) Journal Article (2 results) (of which Int'l Joint Research: 1 results,  Peer Reviewed: 2 results) Presentation (5 results) (of which Int'l Joint Research: 1 results,  Invited: 3 results)

  • [Int'l Joint Research] CERN(スイス)

    • Related Report
      2021 Annual Research Report
  • [Int'l Joint Research] CERN(スイス)

    • Related Report
      2020 Research-status Report
  • [Int'l Joint Research] CERN(スイス)

    • Related Report
      2019 Research-status Report
  • [Journal Article] The large COMPASS polarized solid ammonia target for Drell?Yan measurements with a pion beam2022

    • Author(s)
      Andrieux V.、Berlin A.、Doshita N.、Finger M.、Finger M.、Gautheron F.、Horikawa N.、Ishimoto S.、Iwata T.、Kisselev Y.、Koivuniemi J.、Kondo K.、Magnon A.、Mallot G.K.、Matou?ek J.、Matsuda T.、Meyer W.、Miyachi Y.、Nukazuka G.、Pe?ek M.、Pires C.、Quintans C.、Reicherz G.、Runkel St.、Srnka A.、Suzuki H.
    • Journal Title

      Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

      Volume: 1025 Pages: 166069-166069

    • DOI

      10.1016/j.nima.2021.166069

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] CERN COMPASSの偏極標的2021

    • Author(s)
      糠塚元気
    • Journal Title

      原子核研究

      Volume: 66suppl.1 Pages: 126-136

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed
  • [Presentation] CERN COMPASS の偏極標的2021

    • Author(s)
      Genki Nukazuka
    • Organizer
      日本のスピン物理学の展望
    • Related Report
      2021 Annual Research Report
    • Invited
  • [Presentation] CERN COMPASS の偏極標的2021

    • Author(s)
      糠塚元気
    • Organizer
      日本のスピン物理学の展望
    • Related Report
      2020 Research-status Report
    • Invited
  • [Presentation] CERN COMPASS における液体水素標的を用いた深非弾性散乱によるミューオン,生成ハドロン方位角分布非対称度の測定2020

    • Author(s)
      糠塚元気,他
    • Organizer
      日本物理学会 2020年秋季大会
    • Related Report
      2020 Research-status Report
  • [Presentation] CERN・COMPASS におけるドレル・ヤン実験の解析状況2020

    • Author(s)
      糠塚元気,他
    • Organizer
      日本物理学会第75回年次大会
    • Related Report
      2019 Research-status Report
  • [Presentation] Pion-induced Drell-Yan experiments with transversely polarized proton target in COMPASS at CERN2019

    • Author(s)
      G. Nukazuka on behalf of the COMPASS Collaboration
    • Organizer
      The 11th Circum-Pan-Pacific Symposium on High Energy Spin Physics
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited

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Published: 2019-04-18   Modified: 2023-01-30  

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