Lattice QCD study for verification and prediction of new hadrons

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K03638
• 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: Kyoto University (2020-2021); High Energy Accelerator Research Organization (2019); University of Tsukuba (2018)
• Principal Investigator: Namekawa Yusuke 京都大学, 理学研究科, 特定研究員 (00377946)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 原子核理論

Outline of Final Research Achievements

We verified our method on scattering amplitude, which is important to clarify the structure of new hadrons. Our method is applied to two-pion system and can reproduce the scattering length and the effective range with high precision. We also calculate kaon form factors and extract a Cabbibo-Kobayashi-Maskawa matrix element, a fundamental parameter of the standard model of particle physics. In addition, unexpected progress is obtained by the Complex Langevin method for QCD at finite temperature and density. Although the application range is limited, a non-perturbative calculation is proven to be successfully performed for QCD at finite density, overcoming the sign problem. This result is the first step toward the non-perturbative evaluation of the medium effect of new hadrons.

Free Research Field

計算物理

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的意義は、ハドロンの構造解析に重要な散乱振幅の計算法を確立できた点が挙げられる。また、ハドロンの形状を記述する崩壊形状因子の精密決定を通して、素粒子標準理論の基礎パラメータであるキャビボ・小林・益川行列要素を決定できたことはハドロン物理的のみならず素粒子論的にも意義深い。加えて、ハドロンに対する有限密度媒質効果も中性子星内部で重要と想定されており、天体学としても意義深い。本成果はハドロンに対する有限温度・有限密度媒質効果の非摂動評価への第一歩となる。