New direction of research on baryon-baryon interactions by hyperon-proton scattering experiments

2023 Fiscal Year Final Research Report

• Project/Area Number: 18H03693
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 15:Particle-, nuclear-, astro-physics, and related fields
• Research Institution: Tohoku University
• Principal Investigator: Miwa Koji 東北大学, 理学研究科, 教授 (50443982)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: ストレンジネス核物理

Outline of Final Research Achievements

Nuclear force, which is the source of the atomic nucleus, is a very complex force that involves quarks, which are the constituent elements of nucleons. In particular, the reason why large repulsive forces occur at close distances where nucleons overlap is still unknown, and it has been pointed out that quarks play an important role. Therefore, it is expected that by investigating the force acting between protons and hyperons containing strange quarks, we will be able to clarify the role of quarks in the nuclear force. We succeeded for the first time in the world in measuring the angular distribution of their sigma particles and proton scattering with high precision by producing a lot of Σ hyperons. In particular, we were the first in the world to derive the strength of the Pauli repulsion between quarks from the differential cross section between Σ+ and protons.

Free Research Field

実験核物理

Academic Significance and Societal Importance of the Research Achievements

本研究において、陽子内のクォークの種類を変化させたΣ粒子と陽子とを散乱させ、クォークのパウリ原理で禁止される状態を作ることで、粒子間に働く力が極端に強い斥力へと変化することを明らかにしました。散乱する2つの粒子が3割程度重なり合うような場合に、核力はまだ引力であるのに対して、Σ+陽子間の力はすでに核力の2倍程度も強い斥力になっていることが、得られた微分断面積を解析することで分かりました。これはパウリ原理による斥力の起源を検証し、その芯の堅さを実測したことに相当します。今まで未知であったクォーク間のパウリ斥力の強さを決定したことで、核力の短距離での斥力の理解が一層進むと考えられます。