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

这笔赠款的支持将用于继续一项专注于核子基本性质的核物理研究计划。该计划以托马斯·杰斐逊国家加速器设施(JLab)为基础，专注于两个目标。该项目的主要目标将是完成两名学生参与的QWeak实验跟踪系统的构建。第二个目标将是为JLab12GeV升级准备物理程序以及设计和建造仪器。量子弱实验是一个破坏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”，预测弱混合角如何随着相互作用期间传递的动量的量而变化。因此，对质子弱电荷的测量将评估标准模型的准确性，并对涉及新物理的相互竞争的理论描述敏感，如果标准模型不足的话。虽然这个由NSF支持的计划将主要构建对QWeek实验至关重要的跟踪系统，但它也将继续发挥重要作用，为JLab 12 GeV升级开发物理程序和仪器。首席研究员是一个物理项目的联合发言人，该项目在能量升级的JLab测量核子的偏振可观测值。所做的测量将限制描述运动学区域这些分布的标准理论预测，在运动学区域，被探测的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。QWeek的粒子跟踪系统的开发和JLab 12 GeV升级是这一计划培养研究生和本科生的手段，从而增强了我们这个技术驱动的社会的智能基础设施。

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.