A Low Energy Standard Model Test via Polarized Electron Scattering at Jefferson Lab

这笔拨款将用于继续开展核物理研究项目，重点研究核子的基本性质。该项目以托马斯·杰斐逊国家加速器设施（JLab）为基础，专注于两个目标。本项目的主要目标是在两名学生的参与下完成Qweak实验的跟踪系统的构建。第二个目标将是为JLab12 GeV升级准备物理程序以及设计和构建仪器。量子弱实验是一种违反宇称的电子散射实验，旨在测量质子的弱电荷。对质子弱电荷的测量可以用来提取一个被称为弱混合角的基本量。目前对粒子相互作用的描述，通常被称为“标准模型”，预测了弱混合角如何随着相互作用中传递的动量量而变化。因此，对质子弱电荷的测量将评估标准模型的准确性，并对涉及新物理学的竞争性理论描述敏感，以防标准模型达不到要求。虽然这个nsf支持的项目将主要构建一个对Qweak实验至关重要的跟踪系统，但它也将继续在开发JLab 12 GeV升级的物理程序和仪器方面发挥重要作用。首席研究员是一个物理项目的联合发言人，该项目将在一个能量升级的JLab中测量可观测到的核子偏振。所做的测量将限制在运动区域描述这些分布的严格理论预测，在运动区域，探测夸克携带大部分核子动量。PI还监督JLab能源升级跟踪系统的设计。为Qweak和JLab 12gev升级开发粒子跟踪系统是该计划教育研究生和本科生的手段，从而增强我们技术驱动社会的智力基础设施。

Support from this grant will be used to continue a program of nuclear physicsresearch focused on the fundamental properties of the nucleon. The program isbased at the Thomas Jefferson National Accelerator Facility (JLab) and isfocused on two objectives. The primary goal of this program will be tocomplete the construction of a tracking system for the Qweak experiment withthe involvment of two students. The second objective will be to prepare aphysics program as well as design and construct instrumentation for the JLab12 GeV upgrade. The Qweak experiment is a parity-violating electron scatteringexperiment designed to measure the weak charge of the proton. A measurementof the proton's weak charge can be used to extract a fundamental quantityknown as the weak mixing angle. The current description of particle interactions,commonly referred to as the "Standard Model", predicts how the weak mixingangle changes with the amount of momentum that is transferred during aninteraction. As a result, a measurement of the proton's weak charge will evaluatethe veracity of the Standard Model as well as be sensitive to competing theoreticaldescriptions involving new physics should the Standard Model fall short.While this NSF-supported program will primarily construct a tracking system critical tothe Qweak experiment, it will also continue to play a major role developing a physicsprogram and instrumentation for the JLab 12 GeV upgrade. The principal investigatoris a co-spokesperson for a physics program to measure polarization observables of thenucleon at an energy upgraded JLab. The measurements made will constrain the starktheoretical predictions describing these distributions at kinematic regions wherethe probed quark carries most of the nucleons momentum. The PI is also supervisingthe design of a tracking system for the JLab energy upgrade. The development of particletracking systems for Qweak and the JLab 12 GeV upgrade is the means through which this programeducates both graduate and undergraduate students thereby enhancing the intellectualinfrastructure of our technology driven society.