RUI: Testing QCD Symmetries via Precision Measurements of Light Pseudoscalar Mesons

RUI：通过光赝标量介子的精密测量测试 QCD 对称性

• 批准号: 1206043
• 负责人: Liping Gan
• 金额: $ 20.9万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1206043&HistoricalAwards=false
• 关键词: RUI; Testing; QCD; Symmetries; via

The Standard Model (SM) is a theory that describes fundamental particles in nature and the interactions between them. While the SM has been successful in explaining many phenomena observed in the laboratory to date, it offers no insight into experimental facts such as the dominance of matter over anti-matter, nor the nature of dark matter and dark energy, which are associated with the rotation curves of the galaxies and the accelerated expansion of the universe. Searching for physics beyond the Standard Model is therefore a well-motivated and important task for physicists. A good way to search for new physics is through tests of fundamental symmetries in different interactions.The goal of this project is to test fundamental symmetries in the electromagnetic and strong interactions via precision measurements on the properties of neutral particles: neutral pion and eta. The radiative decay width of the neutral pion plays a key role that bridges chiral symmetry spontaneous breaking and our understanding of QCD (a theory describing the strong interaction). On the other hand, the measurement of the eta radiative decay width will reveal the effect of explicit symmetry breakings of chiral symmetry, isospin, and SU(3) by the light-quark masses. In addition, the measurements of branching ratios or upper limits for various rare and forbidden decays of the eta will provide sensitive probes to test the violations of charge conjugation C, parity P, and time reversal T, as well as CP symmetries, and search for new physics beyond the Standard Model. The results of this project will provide clues to some important questions, such as: "why is our observed universe dominated by matter over anti-matter?", and "what are the masses of the light quarks?"This project will engage undergraduate students as key contributors. It will create a research-enriched learning environment, explore new approaches to recruiting prospective students, and develop new courses which are research related. Students working in an international collaboration will enhance their international experience and gain global perspectives.

标准模型（SM）是一种描述自然界中基本粒子及其之间的相互作用的理论。 尽管SM已经成功地解释了迄今为止在实验室中观察到的许多现象，但它尚未深入了解实验事实，例如物质在反物质上的优势，也没有暗示与暗物质和暗能量的性质，这与星系的旋转曲线以及宇宙的加速膨胀有关。因此，对于物理学家而言，搜索超出标准模型的物理学是一项精力促进且重要的任务。寻找新物理学的一种好方法是通过测试不同相互作用中的基本对称性。该项目的目的是通过对中性颗粒的性质：中性胎胎和ETA进行精确测量测量电磁和强相互作用的基本对称性。 中性倾斜的辐射衰减宽度起着桥接手性对称性自发断裂和我们对QCD的理解（描述强相互作用的理论）的关键作用。 另一方面，ETA辐射衰减宽度的测量将揭示出轻夸克质量的手性对称性，同胞和SU（3）的显式对称性破裂的影响。此外，针对ETA的各种稀有和禁止衰减的分支比率或上限的测量值将提供敏感的探针，以测试违反电荷共轭C，奇偶校验P和时间逆转T的违规，以及CP对称性，以及在标准模型之外寻找新物理学。该项目的结果将为一些重要问题提供线索，例如：“为什么我们观察到的宇宙以反物质而占主导地位？”和“光夸克的群众是什么？”这个项目将吸引本科生作为关键贡献者。它将创建一个富含研究的学习环境，探索招募潜在学生的新方法，并开发与研究有关的新课程。 从事国际合作的学生将增强他们的国际经验并获得全球观点。