Study of Neutron Stars and Elucidation of origin of hadron masses using chiral effective models

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K03927
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Nagoya University
• Principal Investigator: Harada Masayasu 名古屋大学, 素粒子宇宙起源研究所, 教授 (40311716)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: パリティ2重項模型 / カイラル対称性 / 核物質 / 中性子星 / 状態方程式 / ヘビーハドロン

Outline of Final Research Achievements

We constructed a PDM-NJL crossover model by using an interpolation method between the equation of state (EOS) in the low-density region based on the parity doublet model (PDM) constructed before this research project and the EOS in the high-density region based on the NJL-type quark model. We then established a method to restrict the chiral invariant mass using restrictions on the internal EOS obtained from neutron star observations. We also constructed a method to obtain the density dependence of quark condensation, etc. in the interpolation region in the PDM-NJL crossover model.
Furthermore, we investigated corrections due to mesons including strange quarks and the a0(980) meson, and found that their effects do not significantly modify the constraints on the chiral invariant mass.

Free Research Field

理論ハドロン物理学

Academic Significance and Societal Importance of the Research Achievements

低密度領域ではハドロン自由度、高密度領域ではクォーク自由度で記述され、両方の領域でカイラル対称性を尊重する統一模型を構築しました。そして、マクロな量である中性子星の質量・半径関係式から、ミクロな量である核子の質量におけるカイラル不変質量に制限をつける手法を確立しました。これにより、我々の質量の起源への手がかりが得られることが期待できます。