Study of the Electroweak Structure of the Nucleon

这个项目寻求对核物理至关重要的两个问题的答案：亚原子物质是如何组织起来的，出现了什么现象？以及“物质结构的基本相互作用是否得到了充分的理解？”粒子物理的标准模型(SM)成功地描述了基本粒子之间的相互作用，但众所周知它是不完整的，因为SM未能描述塑造我们宇宙的现象，如物质和反物质之间的差异或暗物质的性质。此外，强力与三个轻基本粒子夸克结合，形成质子和中子的大质量复合粒子的机制，在数量上还没有得到很好的理解。宇宙中99%以上的可见物质质量是由这种强大的力产生的。在这种情况下，PI参与了在托马斯·杰斐逊国家加速器设施使用电子束的两个实验计划，第一个是调查质子的内部结构，作为研究强力性质的一种手段，第二个是通过使用精确的标准模型预测执行相互作用的精确测量来搜索标准模型之外的物理。PIS将培训两名研究生和本科生开展研究计划，并将通过“收养物理学家”计划参与STEM外展活动。该项目将部分支持使用电子与质子的深度虚拟康普顿散射，以制作质子内部结构的三维断层图像，可以用来测试强力模型。罗氏是JLab E12-06-114实验的发言人之一，该项目将为该实验的数据获取和数据分析提供支持。这项实验的直接目标是检验用于解释这类实验的广义部分子分布公式所基于的标度假设。该奖项支持的第二个项目将进一步促进PI及其学生参与QWEAK和Moller的JLab宇称违反电子散射实验。这些实验通过研究电子-质子和电子-电子散射中的电磁力和弱力来检验标准模型。PIS将继续与QWEAK合作，直到最终结果公布，并将利用他们在数据获取和软件开发方面的专业知识来准备穆勒实验。

This project seeks answers to two of the overarching questions central to nuclear physics: "How does subatomic matter organize itself and what phenomena emerge?", and "Are the fundamental interactions that are basic to the structure of matter fully understood?". The Standard Model (SM) of particle physics is successful at describing interactions of elementary particles, but it is known to be incomplete, because the SM fails to describe phenomena that shape our universe, like the difference between matter and anti-matter or the nature of dark matter. Furthermore, the mechanisms by which the strong force binds three light elementary particles, quarks, to make massive composite particles, proton and neutrons, are not well understood quantitatively. Over ninety nine percent of the mass of the visible matter in the universe is generated by the strong force in this way. In this context, the PIs are involved in two experimental programs using the electron beam at the Thomas Jefferson National Accelerator Facility, first to investigate the internal structure of the proton as a means of investigating the nature of the strong force, and second to search for physics beyond the Standard Model by performing precision measurements of interactions with precise Standard Model predictions. The PIs will train two graduate students and undergraduate students in carrying out the research program, and will engage in STEM outreach activities through the "Adopt a physicist" program. This project will support in part the use of Deeply Virtual Compton Scattering of electrons from the proton to produce a 3-D tomographic picture of the internal structure of the proton against which models of the strong force can be tested. Roche is one of the spoke persons for experiment E12-06-114 at JLab, and this project will support the data taking and data analysis for this experiment. The immediate goal of this experiment is to test the hypothesis of scaling on which the Generalized Parton Distribution formalism used to interpret this kind of experiments is based. The second project supported by this award will further the involvement of the PIs and their students in the JLab parity violating electron scattering experiments, QWEAK and MOLLER. These experiments test the Standard Model by studying the electromagnetic and weak forces in electron-proton and electron-electron scattering. The PIs will continue their work with QWEAK up to publication of the final results, and will use their expertise in data acquisition and software development for the preparation of the MOLLER experiment.