ヒッグス粒子発見後の素粒子物理学の新展開～LHCによる真空と時空構造の解明～

• Project Area: New expansion of particle physics of post-Higgs era by LHC revealing the vacuum and space-time structure
• Project/Area Number: 16H06488
• 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: The University of Tokyo
• Principal Investigator: 浅井 祥仁 東京大学, 大学院理学系研究科(理学部), 教授 (60282505)
• Project Period (FY): 2016-06-30 – 2021-03-31
• Project Status: Granted (Fiscal Year 2020)
• Budget Amount: ¥21,840,000 (Direct Cost: ¥16,800,000、Indirect Cost: ¥5,040,000); Fiscal Year 2020: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2019: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2018: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2017: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2016: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
• Keywords: LHC / 超対称性粒子 / ヒッグス粒子 / 暗黒物質

Outline of Annual Research Achievements

ヒッグス粒子の発見により、「素粒子」自体の研究から、素粒子を使って「時空や真空」を探る新しい段階へ進みつつある。本領域は、衝突エネルギーを倍増させたLHC加速器を用いて、H27年度からH30年度まで合わせて、170fb-1近いデータを収集できた。予測を超える大きな成果であり、４つの実験計画班を中心に領域全体で実験遂行を行った成果である。
1) ヒッグス粒子と他の素粒子との結合の強さを測定した。力を伝えるゲージ粒子との結合は、2012年の発見の段階で測定されていたが、28,29年度のエネルギーを倍増した実験から、物質を形成するフェルミオンとの結合も測定し、ボトムクォーク(平成30年8月プレスリリース)、トップクォーク（平成30年6月プレスリリース）、タウレプトンとの結合の強さを誤差10-20％で測定した。フェルミ粒子の質量起源もヒッグス粒子であることが分かった。研究項目Bの成果ではあるが、データクォリティーや較正、バックグラウンドの解明など、領域全体で望んだ成果である。これらの研究の主責任者や副責任者を、本領域の研究者が務めるなど中心的な役割を果たしてきた。
2）時空の研究で、超対称性に起因する暗黒物質の探索を精力的にLHCで行い、従来のBino中心の研究から、Higgsino/Wino粒子を探索する消失する飛跡検出器の探索方法を本領域が開発提案して、新しい方法に依る探索が行われた。

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

H27年度からH30年度まで合わせて、170fb-1近いデータを収集できた。これから、これらのデータを用いた解析を進めていく、H29年度までのデータ解析を進め論文として発表することは、世界中の研究者のグループ全体で議論した結果、行わないこととしたため、H29年度いっぱいのデータは、上に挙げたヒッグスの結合強度測定以外は行われなかったが、全てのデータを用いた新しい解析方法の確立と、将来計画のTDRの作成などを行った。H30年11月に東京で本領域が主催して、LHCでのヒッグス粒子の詳細から、真空の構造を探り、宇宙のバリオン優位の起源などの解明を進める国際会議を開催した。

Strategy for Future Research Activity

H27年度からH30年度まで合わせて、170fb-1近いデータを収集できた。それらのデータの解析を進め、
1)現在観測されている小さな乖離（2-3σ程度）の理解、LHCbでのアノマリーに対応する探索を進める。
2)超対称性粒子や電弱対称性の破れの起源の可能性となる現象の探索は、より系統的に行い、漏れがないように進める。特に、探索している粒子（グルイーノやスカラートップクォーク、チャージーノなど）がニュートラリノとの質量差が比較的小さい領域は、検出器の理解やバックグラウンドの理解が鍵になるため、領域全体や公募研究の成果とあわせて情報を共有して研究を進めていく。

Research Products

• [Int'l Joint Research] INFN Roma-I/INFN Pisa/University of Florence(イタリア)
• [Int'l Joint Research] CERN(スイス)
• [Int'l Joint Research] SLAC/Boston University/University of Michigan(米国)
• [Int'l Joint Research] Mac-Planck Institute(ドイツ)
• [Int'l Joint Research] Durham University/University of Cambridge(英国)
• [Int'l Joint Research]
• [Int'l Joint Research] INFN Roma-I/INFN Pisa/University of Florence(イタリア)
• [Int'l Joint Research] CERN(スイス)
• [Int'l Joint Research] SLAC/Boston University/University of Michigan(米国)
• [Int'l Joint Research] Mac-Planck Institute(ドイツ)
• [Int'l Joint Research] Durham University/University of Cambridge(英国)
• [Int'l Joint Research]
• [Int'l Joint Research] INFN Roma-I/INFN Pisa/University of Florence(イタリア)
• [Int'l Joint Research] CERN(スイス)
• [Int'l Joint Research] SLAC/Boston University/University of Michigan(アメリカ)
• [Int'l Joint Research] Mac-Planck Institute(ドイツ)
• [Int'l Joint Research] Durham University/University of Cambridge(イギリス)
• [Int'l Joint Research]
• [Journal Article] Search for long-lived, massive particles in events with displaced vertices and missing transverse momentum in sqrt(s) =13 TeV pp collisions with the ATLAS detector (2018)
  • Author(s): M. Aaboud, K. Hanagaki, J. Tojo, F. Ukegawa, et al. [ATLAS Collaboration]
  • Journal Title: Physical Review D Volume: 97 Pages: 052012-052012
  • DOI: 10.1103/physrevd.97.052012
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector (2018)
  • Author(s): ATLAS Collaboration
  • Journal Title: Physical Review D Volume: 97 Pages: 072003-072003
  • DOI: 10.1103/physrevd.97.072003
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for W W/W Z resonance production in lνqq final states in pp collisions at root(s)=13 TeV with the ATLAS detector (2018)
  • Author(s): The ATLAS collaboration (M. Aaboud, M. Ishino, H. Nanjo, T. Sumida, K. Yorita et al.)
  • Journal Title: Journal of High Energy Physics (JHEP) Volume: 3 Pages: 042-042
  • DOI: 10.1007/jhep03(2018)042
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Model independent evaluation of the Wilson coefficient of the Weinberg operator in QCD (2018)
  • Author(s): T. Abe, J. Hisano and R. Nagai
  • Journal Title: Journal of High Energy Physics Volume: 3 Pages: 175-175
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for squarks and gluinos in events with an isolated lepton, jets, and missing transverse momentum at sqrt(s) = 13 TeV with the ATLAS detector (2017)
  • Author(s): T.Saito et al., ATLAS Collaboration
  • Journal Title: Phys. Rev. D Volume: 96 Pages: 112010-112010
  • DOI: 10.1103/physrevd.96.112010
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Evidence for the H→bbbar decay with the ATLAS detector (2017)
  • Author(s): Aaboud M. et. al. (The ATLAS collaboration)
  • Journal Title: JHEP Volume: 2017 Pages: 024-024
  • DOI: 10.1007/jhep12(2017)024
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for new phenomena with large jet multiplicities and missing transverse momentum using large-radius jets and flavour-tagging at ATLAS in 13 TeV pp collisions (2017)
  • Author(s): T.Saito et al., ATLAS Collaboration
  • Journal Title: J. High Energ. Phys. Volume: 12 Pages: 1-50
  • DOI: 10.1007/jhep12(2017)034
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Subnanosecond time-to-digital converter implemented in a Kintex-7 FPGA (2017)
  • Author(s): Sano Y.、Horii Y.、Ikeno M.、Sasaki O.、Tomoto M.、Uchida T.
  • Journal Title: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 874 Pages: 50-56
  • DOI: 10.1016/j.nima.2017.08.038
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Search for additional neutral Higgs bosons in the MSSM (2018)
  • Author(s): J. Tanaka
  • Organizer: ICHEP2018
  • Int'l Joint Research
• [Presentation] Status and highlights from the ATLAS experiment (2018)
  • Author(s): K. Nagano
  • Organizer: LHCP2018
  • Int'l Joint Research / Invited
• [Presentation] Single Event Upsets in the ATLAS IBL Frontend ASICs (2018)
  • Author(s): Y. Takubo
  • Organizer: Pixel2018
  • Int'l Joint Research
• [Presentation] Study of efficiency and noise of fine pitch planar pixel detector for ATLAS ITk upgrade (2018)
  • Author(s): K. Nakamura
  • Organizer: Pixel2018
  • Int'l Joint Research
• [Presentation] Searches for new physics in final states with top quarks with ATLAS (2018)
  • Author(s): M. Aoki
  • Organizer: LHCP2018
  • Int'l Joint Research
• [Presentation] Coupling and mass with 13 TeV data and expectations (2017)
  • Author(s): S. Oda
  • Organizer: 52nd Recontres de Moriond in Electroweak Interactions and Unified Thories
  • Int'l Joint Research
• [Presentation] Measurements of ttbar+X using the ATLAS detector (2017)
  • Author(s): K. Kawade
  • Organizer: EPS-HEP 2017
  • Int'l Joint Research
• [Presentation] ATLAS Detector Performance in Run2 and Upgrade Plans (2017)
  • Author(s): Masaya Ishino (for ATLAS collaboration)
  • Organizer: High-Energy Physics International Conference in Quantum Chromodynamics
  • Int'l Joint Research
• [Presentation] Mono-jet searches (2017)
  • Author(s): Osamu Jinnouchi (for ATLAS and CMS collaborations)
  • Organizer: DM @ LHC 2017
  • Int'l Joint Research
• [Presentation] Baryon-number violating nucleon decay - Review from theoretical (2017)
  • Author(s): Junji Hisano
  • Organizer: NNN17
  • Int'l Joint Research
• [Presentation] Searches for Beyond SM Higgs bosons (2017)
  • Author(s): Soshi Tsuno
  • Organizer: The 28th International Symposium on Lepton Photon Interactions at High Energies
  • Int'l Joint Research
• [Funded Workshop] HPNP2019 (2019)
• [Funded Workshop] DIS2018 (2018)
• [Funded Workshop] ATLAS Overview Week (2018)
• [Funded Workshop] HC2018 (2018)
• [Funded Workshop] 新テラスケール研究会 (2018)
• [Funded Workshop] AJ物理ワークショップ (2018)
• [Funded Workshop] 新テラスケール研究会 (2017)
• [Funded Workshop] Anomaries in b to sll and its implications (2017)
• [Funded Workshop] 新テラスケール研究会 (2017)