Strange Form Factors and a Low Energy Standard Model Test

奇怪的外形和低能耗标准模型测试

• 批准号: 0457163
• 负责人: Mark Pitt
• 金额: $ 28.2万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0457163&HistoricalAwards=false
• 关键词: Strange; Form; Factors; Low; Energy

This grant supports research that seeks the answer to two fundamental questions about matter. The first is what role does the sea of strange quark-antiquark pairs in the nucleon play in the determination of its electromagnetic properties? We are participating in the G0 experiment at Thomas Jefferson National Accelerator Facility to address this issue. The experiment measures the parity-violating asymmetry in the scattering of polarized electrons from the proton and deuteron over a wide range of momentum transfers; this will allow for the strange electric and magnetic form factors to be separately extracted. This experiment will be in a data-taking and analysis phase during this grant period. The second question is whether or not there is any new physics beyond the Standard Model of electroweak physics. This question will be addressed by the Qweak experiment at TJNAF, which will measure the proton's neutral weak charge via parity-violating electon scattering at very low momentum transfer. The proton's weak charge has a well-defined prediction in the Standard Model; a precise measurement of it is sensitive to many poplular scenarios for extending the Standard Model. This experiment will be in a construction and early data-taking phase during the period of this grant. Our group will design and construct three pieces of hardware for the Qweak experiment - a set of drift chambers, a luminosity monitor, and a mini-torus magnet. These projects involve many hardware and software tasks that will contribute to the education of a postdoctoral fellow and graduate and undergraduate students working on the project.

这笔赠款支持寻求有关物质的两个基本问题答案的研究。第一个问题是核子中的奇异夸克-反夸克对海在确定其电磁特性方面发挥什么作用？我们正在参与托马斯·杰斐逊国家加速器设施的 G0 实验来解决这个问题。该实验测量了质子和氘核的极化电子在大范围的动量转移中散射的宇称破坏不对称性；这将允许单独提取奇怪的电磁形状因素。在此资助期间，该实验将处于数据采集和分析阶段。第二个问题是除了弱电物理标准模型之外是否还存在新的物理现象。 TJNAF 的 Qweak 实验将解决这个问题，该实验将通过在非常低的动量转移下违反宇称的电子散射来测量质子的中性弱电荷。质子的弱电荷在标准模型中有明确的预测；它的精确测量对于扩展标准模型的许多流行场景都很敏感。在本次拨款期间，该实验将处于构建和早期数据采集阶段。我们的小组将为 Qweak 实验设计和构建三件硬件——一组漂移室、一个光度监视器和一个微型环面磁铁。这些项目涉及许多硬件和软件任务，这些任务将有助于从事该项目的博士后研究员以及研究生和本科生的教育。