Revealing the standard model and searches for new physics beyond the standard model via precision top quark measurements

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14485
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Shinshu University
• Principal Investigator: Kawade Kentaro 信州大学, 学術研究院理学系, 助教 (90749243)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: トップクォーク

Outline of Final Research Achievements

In this research project, we focus on the top quark which is the heaviest elementary particle in the Standard Model, with the aim of performing precise measurements of its properties to test the Standard Model and search for deviations due to the presence of new physics. During this research, we achieved significant systematic error reduction by applying a Fully Bayesian Unfolding method that treats systematic errors as nuisance parameters. As a result, we succeeded in finding the first evidence of top quark charge asymmetry. Additionally, we worked on improving analysis methods using machine learning and AI, developing kinematic reconstruction techniques and flavor tagging methods, and demonstrating certain improvements over existing methods. These achievements can be applied to future precision measurements and show promising potential for further development.

Free Research Field

素粒子実験

Academic Significance and Societal Importance of the Research Achievements

トップクォークの有限の荷電非対称度は標準理論でも予言されているが、その値は0に近く超高精度な測定が要求される。この精度での測定手法が達成されたのは初めてであり、その手法を広く応用していくことで標準理論に隠れた新物理の僅かな兆候を探す手段が確率されたことにもなりうる。これは15年に渡る様々な新物理探索にもかかわらず未だ発見されない新物理探索の状況を変える可能性もある。