Study of the mass modification of the rho meson in the nuclei using the high luminosity gamma beam

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01115
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Kyoto Sangyo University
• Principal Investigator: NIIYAMA Masayuki 京都産業大学, 理学部, 教授 (90455361)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 原子核物理 / ハドロン物理 / ハドロン質量の起源

Outline of Final Research Achievements

The origin of the mass of nucleons, which constitute the bulk of the mass of matter, is attributed to quark condensation, a phenomenon where quarks and antiquarks pair up and condense in the vacuum. It is hypothesized that quark condensation varies with environmental factors such as temperature and density, leading to corresponding changes in the mass of hadrons such as nucleons. However, experimental results regarding the change in hadron mass due to environmental variations are inconclusive, with some experiments indicating changes and others showing no change. In this study, we developed a detector at the SPring-8 facility in western Harima, Hyogo Prefecture, to measure the mass of the rho meson in atomic nuclei using a photon beam. By measuring the invariant mass of particles resulting from the decay of rho mesons within atomic nuclei, we aim to establish a process that will clarify the mass of rho mesons in nuclear environments.

Free Research Field

原子核物理

Academic Significance and Societal Importance of the Research Achievements

ヒッグス粒子の発見によって素粒子の質量の起源は広く知られるようになってきた。しかし，身の回りの物質の質量の起源であるハドロンの質量が強い相互作用によって生成されていることは社会的には認知されていない。本研究の最終目標である原子核中でのハドロンの質量の研究を進めることで，身の回りの質量の起源について認知度を上げることができる。本研究開始前には光子ビームでの実験を再検証できる施設は世界的に存在しなかったが，本研究によって検証実験の準備を進めることができた。