RUI: Symmetry Tests of Standard Model and Beyond via Light Meson Decays

该项目的目标是测试电磁和强相互作用中的基本对称性。 通过对Jefferson实验室低质量中性介子性质的精确测量，本研究旨在通过提供一些基本问题的线索来理解自然，例如：（1）为什么夸克被限制在强子中？(2)轻夸克的质量是多少？(3)为什么观测到的宇宙中物质比反物质占优势？（4）什么是暗物质？该项目还将提供很好的机会，让本科生参与前沿研究。它将创造一个研究丰富的学习环境，探索新的方法来招募未来的学生，并开发与研究相关的新课程。PI将作为实验的发言人发挥领导作用：（1）完成中性π介子寿命精确测量的数据分析;（2）优化和准备一项经批准的测量η介子辐射衰变宽度的实验;（3）在D厅调试和运行一台新的成对光谱仪，并与GdX实验同时采集η介子衰变数据;（4）领导杰斐逊实验室“埃塔工厂”计划的发展。对η介子各种罕见和禁戒衰变的测量将为可能存在的新作用力提供灵敏的探针，这将扩展我们对暗物质的认识，并探索解释宇宙中物质和反物质不对称性所需的CP破坏的新来源。 这些超越标准模型的新力量的发现将对推进我们对自然的理解产生深远的影响。

The goal of this project is to test fundamental symmetries in the electromagnetic and strong interactions. By doing precise measurements of the properties of low-mass neutral mesons at Jefferson Lab, this research aims at understanding Nature by providing clues to some fundamental questions, such as: (1) Why are quarks confined inside of hadrons?; (2) What are the masses of the light quarks?; (3) Why is the observed universe dominant by matter over anti-matter?; and (4) What is dark matter? This project will also offer great opportunities to engage undergraduate students in cutting edge research. It will create a research-enriched learning environment, explore new approaches to recruiting prospective students, and develop new courses that are research-related. The PI will play a leadership role as a spokesperson for the experiments: (1) completing data analysis of a precision measurement of the neutral pion lifetime; (2) optimizing and preparing an approved experiment to measure the radiative decay width of the eta meson; (3) commissioning and operating a new pair spectrometer in Hall D and taking data on eta-meson decay in parallel with the GlueX experiment; and (4) leading the development of the Jefferson Lab "Eta Factory" program. Measurements of various rare and forbidden decays of the eta mesons will provide sensitive probes for possible existence of new forces, which will extend our knowledge to the dark matter and explore new sources of CP violation needed to explain the matter and anti-matter asymmetry in the universe. The discovery of such new forces beyond Standard Model would have far-ranging implications to advance our understanding of nature.