超対称性の発見で構築する新たな時空像

2016 Fiscal Year Annual Research Report

• Project Area: New expansion of particle physics of post-Higgs era by LHC revealing the vacuum and space-time structure
• Project/Area Number: 16H06489
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: 陣内 修 東京工業大学, 理学院, 准教授 (50360566)
• Co-Investigator(Kenkyū-buntansha): 中本 建志 大学共同利用機関法人高エネルギー加速器研究機構, 超伝導低温工学センター, 教授 (20290851) ; 浅井 祥仁 東京大学, 大学院理学系研究科(理学部), 教授 (60282505) ; 田中 純一 東京大学, 素粒子物理国際研究センター, 准教授 (80376699)
• Project Period (FY): 2016-06-30 – 2021-03-31
• Keywords: LHC加速器 / ATLAS検出器 / 超対称性粒子探索 / 余剰次元探索 / LHC高輝度化アップグレード / ビーム分離用大口径超伝導双極磁石

Outline of Annual Research Achievements

平成28年度のLHCは前年度に引き続き13TeVで運用された。加速器の運転状況は大幅に改善され、積分ルミノシティ36fb-1に相当するデータを収集した。28年度前半（13fb-1)までのデータ解析を行った。本計画研究では3つの成果が得られた。
(1) グルイーノ、スカラー・トップ生成チャンネルなど、断面積の大きな生成プロセスを重点的に攻め、超対称性粒子探索を推進した。27年度のデータ解析時に見られていた、超過チャンネル（1レプトンチャンネルや、Z+消失エネルギーチャンネル等、それぞれ有意度約2σ）を、28年度前半データで追認し、それぞれ有意度が1-2σまで下がることを確かめた。最終的に有意な超過はなく、グルイーノ、スカラー・トップそれぞれの質量下限1.8TeV、1.0TeVを得た。
(2) 電弱生成などの低断面積チャンネルや、質量スペクトルが縮退したシナリオ等、データ増加が見込まれる次年度以降に重要となるチャンネルに関して、事象選別の最適化や低運動量レプトンの検出手法の工夫など、詳細な検討を進めた。
(3) 更に重い超対称粒子研究を進める上で、加速器の性能向上は必須となる。2024年に建設が始まるLHC高輝度化アップグレードに向けて、ビーム分離用大口径超伝導双極磁石の2m長モデル磁石1号機を試作した。積分ルミノシティは現行LHCの10倍を目標としており、超伝導磁石に対する放射線（40MGy）並びに入熱量（3mW/cm3）について、厳しい仕様を満たすことが求められる。モデル磁石には、新規開発した耐放射線ガラス繊維強化プラスチックを採用し、磁石構造にも冷却性能を向上する工夫を施した。1.9Kにおいて励磁試験を行い、定格電流を超える13.5kAまで通電できることを検証した。磁場計算結果と矛盾しない測定結果が得られ、基本的な磁石設計並びに製作方法を確立できた。

Current Status of Research Progress

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

Reason

超対称性粒子は発見されていないが、各種探索チャンネルで厳しい質量下限等の制限を課す成果をあげている。実験が行われているCERNに複数の若手研究者、大学院生を長期派遣し、現地での研究体制を整えた。国際研究グループの中で活動し、何名かは解析責任者に就任するなど、国際協力の中核となり研究を進めている。終状態に応じて解析手法を分類し、系統的に超対称性探索をカバーしている。また高輝度アップグレードに向けた超伝導磁石の開発も計画通りに進んでいる。

Strategy for Future Research Activity

(1) データ量の増加に伴い重要となる、電弱生成など低断面積の超対称性生成プロセスを探索の中心に据える。より高質量領域を対象とすると、主に寄与するバックグランドの種類がこれまでと異なるものになる。評価手法を新たに検討する。
(2) 超対称性が検出上の理由から「隠れている」可能性を検討し、質量の縮退を仮定する模型や、長寿命粒子の探索モード等、幅広く探索チャンネルをカバーする。
(3) 最近のCERNからの仕様変更を反映した2mモデル磁石2号機を開発し、性能評価を行う。将来の次世代エネルギーフロンティア加速器向け高磁場超伝導磁石のため、高臨界電流Nb3Sn超伝導線の開発を行う。

Research Products

• [Int'l Joint Research] CERN(Switzerland)
  • Country Name: Switzerland
  • Counterpart Institution: CERN
• [Int'l Joint Research] INFN Genova(Italy)
  • Country Name: Italy
  • Counterpart Institution: INFN Genova
• [Journal Article] Fabrication and Test Results of the First 2 m Model Magnet of Beam Separation Dipole for the HL-LHC Upgrade (2017)
  • Author(s): M. Sugano, T. Nakamoto, S. Enomoto, H. Kawamata, N. Okada, R. Okada, K. Sasaki, T. Ogitsu, N. Kimura, K. Tanaka, H. Ohata, M. Iida, N. Higashi, N. Takahashi, S. Sugawara, A. Musso, E. Todesco
  • Journal Title: IEEE Transactions on Applied Superconductivity Volume: 27巻 Pages: 4002409
  • DOI: 10.1109/TASC.2017.2657763
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Magnetic Field Measurement of 2-m-Long Model of Beam Separation Dipole for the HL-LHC Upgrade (2017)
  • Author(s): Shun Enomoto, Michinaka Sugano, Tatsushi Nakamoto, Naoki Okada, Hiroshi Kawamata, Ken-ichi Sasaki, Kenichi Tanaka, Hirokatsu Ohhata, Masahisa Iida, Ryutaro Okada, Naoto Takahashi, Shigekatu Sugawara, Norio Higashi, Toru Ogitsu, Nobuhiro Kimura, Andrea Musso, Ezio Todesco
  • Journal Title: IEEE Transactions on Applied Superconductivity Volume: 27巻 Pages: 600705
  • DOI: 10.1109/TASC.2017.2650958
• [Journal Article] Search for direct top squark pair production in events with a Higgs or Z boson, and missing transverse momentum in √s = 13 TeV pp collisions with the ATLAS detector (2017)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: JHEP Volume: 1708巻 Pages: 006(p1-29)
  • DOI: 10.1007/JHEP08(2017)006
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb－1 of √s = 13 TeV pp collision data with the ATLAS detector (2017)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: JHEP Volume: 1709巻 Pages: 084(p1-43)
  • DOI: 10.1007/JHEP09(2017)084
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for new phenomena in a lepton plus high jet multiplicity final state with the ATLAS experiment using √s = 13 TeV proton-proton collision data (2017)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: JHEP Volume: 1710巻 Pages: 088(p1-51)
  • DOI: 10.1007/JHEP09(2017)088
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for new phenomena in events containing a same-flavour opposite-sign dilepton pair, jets, and large missing transverse momentum in √s = 13 TeV pp collisions with the ATLAS detector (2017)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 77巻 Pages: 144(p1-63)
  • DOI: 10.1140/epjc/s10052-017-4700-5
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Development Status of a 2-m Model Magnet of Beam Separation Dipole for the HL-LHC Upgrade (2016)
  • Author(s): M. Sugano, S. Enomoto, T. Nakamoto, H. Kawamata, N. Okada, R. Okada, N. Higashi, T. Ogitsu, K. Sasaki, N. Kimura, Y. Ikemoto, N. Takahashi, A. Musso, Q. Xu, E. Todesco
  • Journal Title: IEEE Transactions on Applied Superconductivity Volume: 26巻 Pages: 4002606
  • DOI: 10.1109/TASC.2016.2528410
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Development of a 200-mm Short Model of Beam Separation Dipole for HL-LHC Upgrade (2016)
  • Author(s): S. Enomoto, M. Sugano, T. Nakamoto, H. Kawamata, R. Okada, N. Okada, N. Higashi, T. Ogitsu, K. Sasaki, N. Kimura, Y. Ikemoto, A. Musso, Q. Xu, E. Todesco
  • Journal Title: IEEE Transactions on Applied Superconductivity, Volume: 26巻 Pages: 4001905
  • DOI: 10.1109/TASC.2016.2529018
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Development of high radiation-resistant glass _ber reinforced plasticswith cyanate-based resin for superconducting magnet systems (2016)
  • Author(s): Akira Idesaki, Tatsushi Nakamoto, Makoto Yoshida, Akihiko Shimada, Masami Iio, Kenichi Sasaki, Michinaka Sugano, Yasuhiro Makida, Toru Ogitsu
  • Journal Title: Fusion Engineering and Design Volume: 112巻 Pages: 418~424
  • DOI: 10.1016/j.fusengdes.2016.06.031
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Dark matter interpretations of ATLAS searches for the electroweak production of supersymmetric particles in √s=8 TeV proton-proton collisions (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: JHEP Volume: 1609巻 Pages: 175(p1-43)
  • DOI: 10.1007/JHEP09(2016)175
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for new phenomena in different-flavour high-mass dilepton final states in pp collisions at √s = 13 Tev with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 76巻 Pages: 541(p1-42)
  • DOI: 10.1140/epjc/s10052-016-4385-1
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for squarks and gluinos in events with hadronically decaying tau leptons, jets and missing transverse momentum in proton_proton collisions at √s = 13 TeV recorded with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 76巻 Pages: 683(p1-48)
  • DOI: 10.1140/epjc/s10052-016-4481-2
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for supersymmetry in a final state containing two photons and missing transverse momentum in √s = 13 TeV pp collisions at the LHC using the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 76巻 Pages: 517(p1-34)
  • DOI: 10.1140/epjc/s10052-016-4344-x
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for bottom squark pair production in proton_proton collisions at √s = 13 TeV with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 76巻 Pages: 547(p1-37)
  • DOI: 10.1140/epjc/s10052-016-4382-4
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for heavy long-lived charged R-hadrons with the ATLAS detector in 3.2 fb－1 of proton--proton collision data at √s = 13 TeV (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Phys.Lett. B Volume: 760巻 Pages: p647-665
  • DOI: 10.1016/j.physletb.2016.07.042
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for top squarks in final states with one isolated lepton, jets, and missing transverse momentum in √s = 13 TeV pp collisions with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Phys.Rev. D Volume: 94巻 Pages: 052009(p1-32)
  • DOI: 10.1103/PhysRevD.94.052009
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for pair production of gluinos decaying via stop and sbottom in events with b-jets and large missing transverse momentum in pp collisions at √s = 13 TeV with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Phys.Rev. D Volume: 94巻 Pages: 032003(p1-32)
  • DOI: 10.1103/PhysRevD.94.03200
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for gluinos in events with an isolated lepton, jets and missing transverse momentum at √s = 13 TeV with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 76巻 Pages: 565(p1-42)
  • DOI: 10.1140/epjc/s10052-016-4397-x
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for squarks and gluinos in final states with jets and missing transverse momentum at √s = 13 TeV with the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Eur.Phys.J. C Volume: 76巻 Pages: 392(p1-29)
  • DOI: 10.1140/epjc/s10052-016-4184-8
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √s = TeV using the ATLAS detector (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Phys. Rev. D Volume: 94巻 Pages: 032005(p1-32)
  • DOI: 10.1103/PhysRevD.94.032005
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Search for metastable heavy charged particles with large ionization energy loss in pp collisions at √s = 13 TeV using the ATLAS experiment (2016)
  • Author(s): The ATLAS collaboration, (M.Aaboud, S.Asai，O.Jinnouchi，J.Tanaka，et al.)
  • Journal Title: Phys.Rev. D Volume: 93巻 Pages: 112015(p1-25)
  • DOI: 10.1103/PhysRevD.93.112015
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Beyond the SM Higgs searches (2016)
  • Author(s): 田中純一
  • Organizer: The fourth annual Large Hadron Collider Physics (LHCP2016)
  • Int'l Joint Research
• [Presentation] LHC高輝度アップグレード用超伝導磁石の開発(8) -2 mモデル磁石の製作および冷却・励磁試験- (2016)
  • Author(s): 榎本瞬
  • Organizer: 第93回低温工学・超電導学会,
• [Presentation] LHC高輝度アップグレード用 超伝導磁石の開発(3) ー 2 mモデル磁石製作 (2016)
  • Author(s): 菅野未知央
  • Organizer: 第13回日本加速器学会年
• [Presentation] LHC高輝度アップグレード用 超伝導磁石の開発(4) -2 mモデル磁石の冷却・励磁試験- (2016)
  • Author(s): 榎本瞬
  • Organizer: 第13回日本加速器学会年会
• [Presentation] Fabrication and Test Results of the First 2 m Model Magnet of Beam Separation Dipole for the HL-LHC Upgrade (2016)
  • Author(s): Michinaka Sugano
  • Organizer: Applied Superconductivity Conference 2016 (ASC2016)
  • Int'l Joint Research / Invited
• [Presentation] Magnetic Field Measurement of 2-m-Long Model of Beam Separation Dipole for the HL-LHC Upgrade (2016)
  • Author(s): Shun Enomoto
  • Organizer: Applied Superconductivity Conference 2016 (ASC2016)
  • Int'l Joint Research
• [Presentation] Development of Radiation Resistant GFRP for Superconducting Magnet in High Intensity Accelerators (2016)
  • Author(s): T. Nakamoto
  • Organizer: Applied Superconductivity Conference 2016 (ASC2016)
  • Int'l Joint Research
• [Book] LHCの物理: ヒッグス粒子発見とその後の展開 (2016)
  • Author(s): 浅井 祥仁
  • Total Pages: 122
  • Publisher: 共立出版
  • ISBN: 978-4320035270