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が得られた。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。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、トップクォーク、タウレプトンとの結合の強さを誤差10-20％で測定した。力を伝えるゲージ粒子ばかりでなく、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。2) 世代の解明：また、第2世代の素粒子であるミュー粒子とヒッグス粒子の結合の強さを測定し、世代の違いをヒッグス粒子が作っていること分かった。3)ヒッグス粒子などの精密測定より、我々の宇宙が安定ではなく、準安定であることが分かった。これは、我々の宇宙の真空が一番エネルギーが低いのではなく、別の最低エネルギーに相当する状態があることを示すものであり、新現象の存在を示唆する結果である。この新現象が何に対応しているかの研究を領域全体で進めている。最近観測されている、フレーバー関係の精密測定と標準理論の予言からの乖離や、muonのg-2の精密測定の結果のズレ、暗黒物質などの成果を包含して、新しい現象の可能性とLHCでの観測が期待される素粒子現象について、複数の可能性まで絞り込んだ。理論と実験や幅広い研究者が参加しており、LHCの第３期実験や公募研究での他の研究と合わせて、その可能性を検証できることがわかった。

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、上の成果が示す様に多くの成果が得られた。新現象のヒントが、どのような物理現象によるものなのかなどの議論を領域全体で進めている。令和2年度は、新型コロナウィルスの影響で、国際会議がキャンセルされるなどの影響を強く受けた。本領域の準備していた国際会議も、１年延期し、テラスケール研究会もオンライン開催になるなどの、研究発表を行い、議論を深める場の確保と言う点では、大きな影響を受けた。

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、muon g-2などの成果と、合わせて本領域で得られたヒントと結びつける研究を領域全体で進める。 2)1)で鍵となるのは、超対称性粒子が暗黒物質となるニュートラリノとの質量差が比較的小さい領域であり、従来の研究ではカバーできていない。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] Max-Plank 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(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]
• [Journal Article] Measurement of the associated production of a Higgs boson decaying into b-quarks with a vector boson at high transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector (2021)
  • Author(s): The ATLAS Collaboration (S.Asai et al)
  • Journal Title: Physics Letters B Volume: 816 Pages: 136204-136204
  • DOI: 10.1016/j.physletb.2021.136204
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector (2021)
  • Author(s): ATLAS Collaboration
  • Journal Title: Physics Letters B Volume: 812 Pages: 135980-135980
  • DOI: 10.1016/j.physletb.2020.135980
  • Peer Reviewed / Open Access / 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 lvqq final states in pp collisions at √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 √ 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→bb 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
  • NAID: 120007134627
  • 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] 「素粒子物理実験」とAIの接点 (2019)
  • Author(s): 田中 純一
  • Organizer: JSAI2019
  • Invited
• [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] Dark Matter searches in the 2020s (2020)
• [Funded Workshop] KEK-PH2020 (2020)
• [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)