New developments in particle physics after the discovery of the Higgs boson: elucidation of the vacuum and the space-time structure with the LHC experiment

2022 Fiscal Year Final 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: 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: Asai Shoji 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
• Keywords: 超対称性粒子 / ヒッグス粒子 / 暗黒物質

Outline of Final Research Achievements

The Higgs boson discovered in LHC Run-1 was throughly studied in un-2 with the collision energy of 13 TeV and about six times higher statistics than Run-1. It was found that the Higgs boson is responsible not only for the mass of the gauge particles i.e. force carriers, but also for the mass of the matter particles. We also found that the Higgs boson is responsible for the three generations of the matter particles, which could be a significant key to the unsolved mojor problem of elementary particles. Also confirmed that the vacuum of our universe is metastable, suggesting the existence of new physics beyond the Standard Model. Systemtical searches for new physics has led to the exclusion of a wide range of parameter spaces and significantly narrowed the region in which new physics may exist. Based on the results obtained from the LHC and other experiments, the phenomenology of the new phsyics which we expect to observe at LHC in the future has been theoretically formulated.

Free Research Field

素粒子実験

Academic Significance and Societal Importance of the Research Achievements

本研究によりヒッグス粒子の性質に関し多くの事実が判明した。素粒子が質量を獲得する機構は標準模型の柱の一つであり，誕生直後の宇宙の相転移やその後の長い年月をかけた宇宙進化の根幹に関わる重大な要素である。本課題の実験結果からヒッグス粒子と関わる粒子の種類，世代の謎を解く鍵が明らかとなり，人類の自然科学に対する認識レベルを大きく前進させることができた。一方，超対称性などの探索からは新粒子は未発見であり，標準模型を超える物理がより重い領域に存在するであろうことが示唆される。ここで得られた実験結果，理論研究から，暗黒物質の候補となる新物理を絞り込めたことで次世代の研究にとり大きなインプットとなる。