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: 16K21730
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Multi-year Fund
• 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 – 2022-03-31
• Project Status: Granted (Fiscal Year 2020)
• Budget Amount: ¥52,650,000 (Direct Cost: ¥40,500,000、Indirect Cost: ¥12,150,000); Fiscal Year 2020: ¥10,530,000 (Direct Cost: ¥8,100,000、Indirect Cost: ¥2,430,000); Fiscal Year 2019: ¥10,530,000 (Direct Cost: ¥8,100,000、Indirect Cost: ¥2,430,000); Fiscal Year 2018: ¥10,530,000 (Direct Cost: ¥8,100,000、Indirect Cost: ¥2,430,000); Fiscal Year 2017: ¥10,530,000 (Direct Cost: ¥8,100,000、Indirect Cost: ¥2,430,000); Fiscal Year 2016: ¥10,530,000 (Direct Cost: ¥8,100,000、Indirect Cost: ¥2,430,000)
• Keywords: 素粒子実験 / 素粒子論 / 加速器

Outline of Annual Research Achievements

LHCのエネルギーが倍増され約170b-1近いデータが蓄積された。このデータを解析して、「世代の解明」、「質量の起源の解明」、「新しい真空の発見（新現象の示唆）」などの多くの成果が得られた。物質を形作る素粒子（フェルミ粒子）、力を伝える素粒子（z、w）は、全く別々の機構ではあるが、発見されたヒッグス場がその源になっていることがわかった。このヒッグス場との結合の強さが O(1)からO(10^-5)と大きく変化することによりさまざまな素粒子の質量や世代が創造されていることが判明した。なぜ、こんなに小さな定数になるのかを国際活動支援班と総括班が中心となって、領域外のストリング理論などと共同で研究を進めていく予定である。
また、ヒッグス場が不安定であり新しい素粒子現象の存在が不可欠であることがわかり、宇宙初期の重力波研究などにより探ることができると領域研究でわかった。これをどう観測に結びつけるかを国際活動支援班と総括班が中心となって進める準備を行っていた。
反面、新型コロナウィルス感染症で、国際的な往来が著しく制限された。更に、令和２年前半は、欧州の多くの研究所が閉鎖されるなどの深刻な影響を受け、令和２年度に再開される予定だったLHC第3期実験などが延期されることになった。本領域では、研究者をLHC実験が行われているCERNに、コロナ以降も派遣を続け、日本国内からリモートで、実験装置自体を開発制御する準備を行っている。リモート国際共同研究実験を通して、海外への出張が困難な学生やスタッフが、実験に参加出来るように準備を進めた。
国際活動支援班は令和2年度は、成果をまとめた国際会議を開催する予定で準備を行ってきたが、コロナの影響で令和3年度へ会議を延期した。

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

新型コロナウィルス感染症のために、研究者が往来できなくなり、これにともない、本領域が企画していた大型国際会議、招聘、がキャンセルになっている。
オンラインで行える物理解析研究は、他分野の技術を積極的に取り入れ研究をすすめた。１）機械学習を用いて、ボトムクォークとヒッグス粒子の結合の強さを世界で初めて観測し、力を伝える素粒子ばかりでなく、物質を形作る素粒子の質量の起源も、同じヒッグス粒子であることを示した。２）ヒッグス粒子を詳細に調べることで、我々の真空が、一番安定な状態ではなく、少しエネルギーが高く不安定であることが判明するなどの重要な成果である。一方、第3期実験を行う予定で準備を進めてきたが、研究所が閉鎖されたり、研究者が集まれなくなったために準備が遅れてしまっており、実験開始が１年遅れてしまった。

Strategy for Future Research Activity

二つの研究課題を令和３年度に推進する。1つ目の若手研究者の海外研究機関への長期滞在を行い、LHCの第3期実験を開始する。R3年度は数名を予定し各計画研究班と協力して、リモートでLHC実験を再開する準備を行う。現地に滞在する研究者と、国内の滞在者が協力して実験を再開する。
年度の後半に、ワクチンにより研究者の往来が可能になる頃に、海外の研究者を招聘し、長期滞在して共同研究を行い、国際会議の開催を通して、領域の成果を国内外に発信する。中規模・小規模のworkshopは、オンラインを中心に開催を行う。

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] 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] Max-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] Max-Planck Institute(ドイツ)
• [Int'l Joint Research] Durham University/University of Cambridge(英国)
• [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] A search for the Zγ decay mode of the Higgs boson in pp collisions at √s=13 TeV with the ATLAS detector (2020)
  • Author(s): ATLAS Collaboration
  • Journal Title: Physics Letters B Volume: 809 Pages: 135754-135754
  • DOI: 10.1016/j.physletb.2020.135754
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Evidence for tt tt production in the multilepton final state in proton-proton collisions at √s=13 TeV with the ATLAS detector (2020)
  • Author(s): ATLAS Collaboration
  • Journal Title: The European Physical Journal C Volume: 80
  • DOI: 10.1140/epjc/s10052-020-08509-3
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Studying gaugino masses in supersymmetric model at future 100 TeV pp collider (2019)
  • Author(s): Asai Shoji、Chigusa So、Kaji Toshiaki、Moroi Takeo、Saito Masahiko、Sawada Ryu、Tanaka Junichi、Terashi Koji、Uno Kenta
  • Journal Title: JHEP05(2019)179 Volume: 2019 Pages: 179-179
  • DOI: 10.1007/jhep05(2019)179
  • Peer Reviewed / Open Access
• [Journal Article] Discovery reach for wino and higgsino dark matter with a disappearing track signature at a 100 TeV pp collider (2019)
  • Author(s): Saito Masahiko、Sawada Ryu、Terashi Koji、Asai Shoji
  • Journal Title: European Physical Journal C Volume: 79 Pages: 469-469
  • DOI: 10.1140/epjc/s10052-019-6974-2
  • Peer Reviewed / Open Access
• [Journal Article] Review of Particle Physics (2019)
  • Author(s): Tanabashi M.、Hagiwara K.、Hikasa K.、Nakamura K.、Murayama H.、et al.
  • Journal Title: Physical Review D Volume: 98 Pages: 030001-030001
  • DOI: 10.1103/physrevd.98.030001
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] FCC-hh: The Hadron Collider (2019)
  • Author(s): A. Abada, S. Asai, J. Tanaka et al
  • Journal Title: European Physical Journal: Special Topics Volume: 228 Pages: 755-1107
  • DOI: 10.1140/epjst/e2019-900087-0
  • 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 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] 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] 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
• [Journal Article] Dark matter physics, flavor physics and LHC constraints in the dark matter model with a bottom partner (2017)
  • Author(s): T.Abe, J.Kawamura, S.Okawa, Y.Omura
  • Journal Title: JHEP Volume: - Pages: 042-042
  • DOI: 10.1007/jhep03(2017)058
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Presentation] Search for Leptoquarks using the ATLAS detector (2020)
  • Author(s): Yasuyuki Okumura
  • Organizer: ICHEP202
  • Int'l Joint Research
• [Presentation] Observations of weak boson scattering with the ATLAS detector (2020)
  • Author(s): Takuya Nobe
  • Organizer: ICHEP2020
  • 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] 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
• [Presentation] The alignment limit in two Higgs doublet models (2017)
  • Author(s): Sabine Kraml
  • Organizer: HPNP2017
  • Place of Presentation: 富山大学（富山県富山市）
  • Int'l Joint Research / Invited
• [Presentation] Flavor physics induced by light Z′ from SO(10) GUT. (2016)
  • Author(s): Y. Omura
  • Organizer: B2Tips workshop
  • Place of Presentation: Munich (Germany)
  • Year and Date: 2016-11-15
  • Int'l Joint Research
• [Presentation] Exploring neutrino mass generation mechanisms via the lepton flavor violating decay of the Higgs boson (2016)
  • Author(s): H. Sugiyama
  • Organizer: DISCRETE2016
  • Place of Presentation: Warszawa (Poland)
  • Int'l Joint Research
• [Presentation] Neutrinos at LHC (2016)
  • Author(s): T. Sumida
  • Organizer: LHC Days 2016
  • Place of Presentation: Split (Croatia)
  • Int'l Joint Research / Invited
• [Funded Workshop] 新テラスケール研究会 (2019)
• [Funded Workshop] HNPN2019 (2019)
• [Funded Workshop] DIS2018 (2018)
• [Funded Workshop] ATLAS Overview Week (2018)
• [Funded Workshop] HC2018 (2018)
• [Funded Workshop] LAr Week March 2018 in Tokyo (2018)
• [Funded Workshop] ATLAS CERN-Tokyo 2017 Winter/Spring Workshop (2017)
  • Place of Presentation: 東京大学（東京都文京区）
  • Year and Date: 2017-03-23
• [Funded Workshop] Physics in LHC and the Early Universe (2017)
  • Place of Presentation: 東京大学（東京都文京区）
  • Year and Date: 2017-01-09