Precision Standard Model Tests With Parity-Violating Electron Scattering

违反宇称电子散射的精密标准模型测试

• 批准号: 1406689
• 负责人: Mark Pitt
• 金额: $ 40.5万
• 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: 2014
• 资助国家: 美国
• 起止时间: 2014-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1406689&HistoricalAwards=false
• 关键词: Precision; Standard; Model; Tests; Parity

This grant supports research that seeks to answer a fundamental question about matter. What is the nature of any new physics not described by the Standard Model - our current understanding of how particles and forces interact? This question will be addressed by precision measurements of the weak charges of the proton and electron. The proton and electron's weak charges are the weak force analogs of the ordinary electric charges of these particles. The weak charges are precisely predicted in the Standard Model. Any deviation of measurements from these predictions could be evidence of as yet undiscovered massive particles that represent new physics beyond our existing understanding. The grant will support graduate and undergraduate students who will form an essential part of this project. The anticipated activities cover a range of hardware and software projects that will provide excellent training for these students. This training in fundamental research provides a strong basis for careers both in basic research and in more applied research and industry. The funds provided by this grant will support activities on two parity-violating electron scattering experiments at Thomas Jefferson National Accelerator Facility (TJNAF). The Qweak experiment will measure the proton's neutral weak charge via parity-violating electron 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 popular scenarios for extending the Standard Model. During the period of this grant, we will perform data analysis leading to the final determination of the proton's weak charge from the Qweak experiment. We will also perform analysis to extract physics results from the Qweak data for two other topics - a probe of hadronic parity violation in the N to Delta transition and a measurement of the transverse asymmetry in Moller scattering. The MOLLER experiment is an approved TJNAF experiment intended for the upgraded 12 GeV TJNAF. It will measure the electron's neutral weak charge by making a precision measurement of the parity-violating asymmetry in the elastic scattering of polarized electrons on unpolarized electrons at a very low momentum transfer. This will result in a determination of the weak mixing angle at low energy with a precision comparable to the best determinations from high energy colliders. It would have excellent sensitivity to many beyond the Standard Model scenarios. During the period of this grant, our group will contribute to the development of this experiment by working on beam charge and position monitor upgrades, luminosity monitor and background detector development and construction, and simulation design studies.

该赠款支持试图回答有关问题的基本问题的研究。标准模型未描述的任何新物理学的性质是什么？我们当前对粒子和力如何相互作用的理解是什么？ 这个问题将通过精确测量质子和电子的弱电荷来解决。 质子和电子的弱电荷是这些颗粒普通电荷的弱力类似物。 弱电荷在标准模型中精确预测。 测量结果与这些预测的任何偏差都可以证明尚未发现的巨大颗粒，这些颗粒代表了我们现有的理解超出我们现有的理解。 该赠款将支持毕业生和本科生，他们将构成该项目的重要组成部分。 预期的活动涵盖了一系列硬件和软件项目，这些项目将为这些学生提供出色的培训。 基础研究中的这种培训为基础研究以及更应用的研究和行业的职业提供了强大的基础。该赠款提供的资金将支持在托马斯·杰斐逊国家加速器设施（TJNAF）的两个平均侵入电子散射实验上的活动。 QWEAK实验将通过在非常低的动量转移下通过平均侵入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具有明确的预测。它的精确度量对扩展标准模型的许多流行场景敏感。在本赠款期间，我们将进行数据分析，从而最终确定质子的弱电荷从QWEAK实验中。 我们还将进行分析，以从QWeak数据中提取物理结果，以获取其他两个主题 - n到三角洲转变中的抗耐药率违规的探针，以及对moller散射中横向不对称的测量。 Moller实验是针对升级的12 GEV TJNAF的批准的TJNAF实验。 它将通过以非常低的动量传递方式对极化电子上极化电子的弹性散射中的平均侵略不对称性进行精确测量来测量电子的中性弱电荷。 这将导致在低能量下的弱混合角，具有与高能量山针的最佳测定相当的精确度。 除了标准模型方案之外，它对许多人都具有出色的敏感性。 在这笔赠款期间，我们的小组将通过进行梁充电和位置监视器升级，光度监控和背景检测器的开发和构建以及仿真设计研究来为该实验的开发做出贡献。

项目成果

Precision measurement of the weak charge of the proton

• DOI: 10.1038/s41586-018-0096-0
• 发表时间: 2018-05
• 期刊: Nature
• 影响因子: 64.8
• 作者: D. Androić;D. Armstrong;A. Asaturyan;T. Averett;J. Balewski;K. Bartlett;J. Beaufait;R. Beminiwattha-R.-Bemin