Precision Standard Model Tests With Parity-Violating Electron Scattering

这笔赠款支持旨在回答有关物质的基本问题的研究。标准模型（我们目前对粒子和力如何相互作用的理解）没有描述的任何新物理学的本质是什么？ 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粒子的普通电荷的弱力类似物。 标准模型中精确预测了弱电荷。 测量结果与这些预测的任何偏差都可能是尚未发现的大质量粒子的证据，这些粒子代表了超出我们现有理解的新物理学。 这笔赠款将支持研究生和本科生，他们将成为该项目的重要组成部分。 预期的活动涵盖一系列硬件和软件项目，将为这些学生提供良好的培训。 这种基础研究培训为基础研究以及更多应用研究和行业的职业生涯提供了坚实的基础。这笔赠款提供的资金将支持托马斯·杰斐逊国家加速器设施（TJNAF）的两个违反宇称电子散射实验的活动。 Qweak 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。在本次资助期间，我们将进行数据分析，最终确定 Qweak 实验中质子的弱电荷。 我们还将进行分析，从 Qweak 数据中提取其他两个主题的物理结果 - N 到 Delta 跃迁中强子宇称破坏的探测和莫勒散射中横向不对称性的测量。 MOLLER 实验是一项经过批准的 TJNAF 实验，旨在用于升级后的 12 GeV TJNAF。 它将通过精确测量在非常低的动量转移下极化电子在非极化电子上的弹性散射中的宇称破坏不对称性来测量电子的中性弱电荷。 这将导致低能量弱混合角的确定，其精度可与高能对撞机的最佳确定相当。 它对标准模型场景之外的许多场景具有出色的敏感性。 在这笔资助期间，我们小组将通过致力于束流电荷和位置监测器升级、光度监测器和背景探测器开发和构建以及模拟设计研究来为该实验的发展做出贡献。

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.