Non-perturbative calculations of the hadronic structure functions for understanding of the universe's matter dominance

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K14309
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Nara Women's University
• Principal Investigator: Ohki Hiroshi 奈良女子大学, 自然科学系, 助教 (50596939)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 格子QCD / 数値シミュレーション / 素粒子標準模型 / 宇宙論 / CP対称性

Outline of Final Research Achievements

The electric dipole moment (EDM) is a key quantity to probe the universe's matter dominance and to test the physics beyond the standard model in particle physics. We develop a new method to compute the nucleon EDM in the presence of the background electric field on a lattice. This method does not require the zero-momentum extrapolation and can suppress the gauge fluctuations, so that it can be applicable to measure other quantities that include gauge fields.
We also study a general dispersion relation of the spectral functions on a lattice, by which we performed a precise measurement of a Kobayashi-Maskawa matrix element |Vus| in combining with an inclusive tau decay experimental data and the lattice hadronic vacuum polarization functions. We then extend the method to the nucleon correlation functions that can be used to study nucleon inclusive decay processes such as a nucleon-neutrino scattering on a lattice.

Free Research Field

素粒子論

Academic Significance and Societal Importance of the Research Achievements

自然界の基本的な対称性であるCP対称性とその破れの起源の探求は、自然界の基本的な物理法則の探求や宇宙の成り立ちに迫る自然科学における根源的な課題と関連する。電気双極子能率はCP対称性の破れを引き起こす代表的な物理現象であるが、従来の研究成果では誤差が大きく、素粒子標準模型やそれを超えた新物理の検証には不十分であり、本研究のように大型計算機を用いた格子理論に基づく第一原理計算による新たな知見が自然界の極微の世界の解明や宇宙の起源に迫る上で重要である。また高エネルギー物理学や宇宙観測など、日本が主導する国際的実験プロジェクトに対する理論的基礎の構築にも貢献する事が出来ると考えられる。