Search for CP violation in a unified flavor structure and its observational verification

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14459
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Saitama University
• Principal Investigator: Yang J.S. Masaki 埼玉大学, 理工学研究科, 非常勤講師 (50815941)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: ニュートリノ振動 / 世代の謎 / CPの破れ

Outline of Final Research Achievements

In this study, we searched for flavor structures with a unified violation of CP symmetry (symmetry between particle-antiparticle) in Yukawa interactions (the force acting between the Higgs boson and ordinary particles and producing mass). As a result, we found a new (generalized) CP symmetry in the Standard Model called diagonal reflection symmetries.

These symmetries restricts the CP violation to the lightest first generation, and in combination with a flavor structure called the four-zero texture, explain the currently observed quark-lepton masses and mixing matrices, and predicts the CP violation in the currently observed neutrino oscillations. Various phenomenological developments of these generalized CP symmetries are presented.

Free Research Field

素粒子物理学（現象論）

Academic Significance and Societal Importance of the Research Achievements

ヒッグス粒子が発見されたとはいえ、その相互作用を決定する原理や法則は未だ謎のまま残されている。『ヒッグスとは何か？』という問いになんらかの形で答えることは、この時代における素粒子理論の主要課題の一つである。ここで発見された新しいCP対称性はヒッグスが第１世代のみを特別扱いすることを示唆し、この性質の解明や新たな展開をもたらすものと考える。