Precision Studies of the Standard Model using Parity-Violating Electron Scattering

为了理解物质的基本结构，大多数物理学家采取了还原论的方法，将物质分解为基本成分：电子、夸克、胶子等等。除了这些已知的基本粒子，它们构成了粒子物理学的标准模型（我们目前关于物质基本粒子及其相互作用的最佳理论），可能存在更多尚未被发现的基本粒子。2该项目支持在托马斯杰斐逊国家加速器设施（杰斐逊实验室）的两个大型实验中精确测量质子和电子的所谓电弱性质的努力。这些测量和标准模型的预测之间的差异将指向标准模型尚未包含的新物理过程。在协议的情况下，某些扩展的标准模型将被排除。精确的电弱测量提供了一个独特的方法来测试粒子物理学的标准模型在低能电子加速器。杰斐逊实验室是目前世界上领先的实验室，这些违反宇称电子散射实验，是唯一适合完成雄心勃勃的Qweak和MOLLER实验。这两个实验的结果，单独的，但特别是与欧洲核子研究中心的大型强子对撞机的结果相结合，将使我们能够限制物理模型超越标准模型。Qweak实验开始于2010年5月，收集数据直到2012年5月。该实验仅用5%的可用数据首次确定了质子的弱电荷，并旨在用完整的数据集对标准模型之外的物理学进行精确测量。研究人员将继续在轨道重建、数据分析和模拟工作中发挥核心作用，这些工作对成功完成实验至关重要。MOLLER实验预计最早将于2017年运行，并将通过测量电子的弱电荷来测量电弱混合角，其精度可与最好的高能测量相媲美。研究人员将在MOLLER实验的径迹重建探测器的开发中发挥主导作用，以及基于极化氢原子气体中的Moller散射的新型电子束偏振计的研制。 这种新的偏振计将允许测量的电子极化所需的精度为0.4%，使用的技术，将适用于其他电子accelerator.The调查人员正在努力增加经济和种族的多样性，通过具体的招聘努力威廉玛丽REU计划的物理。 调查人员致力于增加物理系和更广泛的社区之间的互动，通过组织“物理节”，每年的物理系开放日，并通过“星期六上午物理”，一个定期的公共宣传讲座系列，针对当地初中和高中学生。

In the quest to understand the fundamental structure of matter, most physicists have taken a reductionist approach by breaking down matter into its elementary constituents: electrons, quarks, gluons, etc. In addition to these known elementary particles that constitute the Standard Model of particle physics (our current best theory of the fundamental particles of matter and their interactions), there may exist more as-of-yet undiscovered elementary particles.This project supports efforts to precisely measure so-called electroweak properties of the proton and of the electron in two large experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). Discrepancies between these measurements and the predictions of the Standard Model will point to new physical processes that are not yet included in the Standard Model. In case of agreement certain extensions to the Standard Model will be ruled out.Precision electroweak measurements present a unique approach to test the Standard Model of particle physics at low-energy electron accelerators. Jefferson Lab is currently the world's leading laboratory for these parity-violating electron scattering experiments, and is uniquely suited to complete the ambitious Qweak and MOLLER experiments. The results of both experiments, by themselves but especially in combination with the results from the Large Hadron Collider at CERN, will allow us to constrain models of physics beyond the Standard Model.The Qweak experiment started in May 2010 and collected data until May 2012. The experiment has performed the first determination of the weak charge of the proton with only 5% of the available data, and is aiming to make a precision measurement sensitive to physics beyond the Standard Model with the full data set. The investigators will continue their central role in the track reconstruction, data analysis, and simulation efforts crucial to the successful completion of the experiment. The MOLLER experiment is expected to run as early as 2017, and will measure the electroweak mixing angle to a precision comparable to the best available high-energy measurements through a measurement of the weak charge of the electron. The investigators will take a leading role in the development of the track reconstruction detectors for the MOLLER experiment, and the development of a novel type of electron beam polarimeter based on Moller scattering in polarized atomic hydrogen gas. This new polarimeter will allow the measurement of the electron polarization to the required precision of 0.4% using a technique that will be applicable at other electron accelerators as well.The investigators are working to increase economic and racial diversity in physics through specific recruiting efforts for the William & Mary REU program. The investigators are committed to increasing interaction between the physics department and the broader community through the organization of "PhysicsFest," a yearly physics department open house, and through "Saturday Morning Physics," a regular public outreach lecture series aimed at local middle and high school students.