Probing the Standard Model and Nuclear Structure with Parity-Violating Electron Scattering

用宇称破坏电子散射探测标准模型和核结构

• 批准号: 1714325
• 负责人: Mark Pitt
• 金额: $ 38万
• 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: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1714325&HistoricalAwards=false
• 关键词: Probing; Standard; Model; Nuclear; Structure

This project 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 at two large collaborative experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Newport News, Virginia. The proton and electron's weak charges are the weak force analogs of the common 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 yet undiscovered massive particles that represent new physics beyond our current understanding. The program will support graduate and undergraduate students and a postdoctoral fellow, who will form an essential part of this project. The anticipated activities cover a range of hardware and software tasks that will provide excellent training for these individuals. 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 project will support activities on three 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 program, the group will primarily be contributing to a complete analysis of the weak charge result as well as finalizing analyses 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 should have excellent sensitivity to many beyond the Standard Model scenarios. During the period of this project, the group will make important contributions to this experiment by working on beam charge and position monitor upgrades, luminosity monitor and background detector development and construction, scanner detector development, and simulation design studies. Neutron radii in neutron-rich nuclear provide an important test of nuclear structure with applications to neutron star structure and heavy ion collisions. The PREX-II and CREX experiments are anticipated to run in this period and determine the neutron radii in lead-208 and calcium-48. The group will provide large angle scattering monitors and a setup for linearity testing and will contribute to the analysis of beam monitoring and modulation data and data-taking shift support.

该项目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？ 这个问题将通过在弗吉尼亚州纽波特纽斯的托马斯杰斐逊国家加速器设施（杰斐逊实验室）的两个大型合作实验中对质子和电子的弱电荷进行精确测量来解决。 质子和电子的弱电荷是这些粒子的公共电荷的弱力类似物。弱电荷在标准模型中得到了精确的预测。 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目前理解的新物理学。该计划将支持研究生和本科生以及博士后研究员，他们将成为该项目的重要组成部分。 预期的活动包括一系列硬件和软件任务，这些任务将为这些人提供出色的培训。 这种基础研究培训为基础研究和更多应用研究和工业的职业生涯提供了坚实的基础。 该项目提供的资金将支持在托马斯杰斐逊国家加速器设施（TJNAF）进行的三个宇称违反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的宇称违反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一个明确的预测;对它的精确测量对许多流行的扩展标准模型的方案很敏感。在该计划期间，该小组将主要致力于对弱电荷结果进行完整分析，并最终完成分析，以从Qweak数据中提取其他两个主题的物理结果-N到Delta转变中的强子宇称违反的探测和Moller散射中横向不对称性的测量。MOLLER实验是一个经过批准的TJNAF实验，旨在升级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对非极化电子的弹性散射中的宇称违反不对称性来测量电子的中性弱电荷。 这将导致在低能量下弱混合角的测定，其精度可与高能对撞机的最佳测定相媲美。 它应该对许多超出标准模型的场景具有出色的敏感性。 在本项目期间，该小组将通过开展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建设、扫描探测器开发和模拟设计研究，为该实验做出重要贡献。丰中子核的中子半径是检验核结构的重要手段，在中子星星结构和重离子碰撞中有重要的应用。 PREX-II和CREX实验预计将在此期间进行，并确定铅-208和钙-48的中子半径。 该小组将提供大角度散射监测器和线性测试装置，并将有助于分析束流监测和调制数据以及数据采集移位支持。

项目成果

Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering

前角弹性电子质子散射中束流法线单自旋不对称性的精密测量

• DOI: 10.1103/physrevlett.125.112502
• 发表时间: 2020
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: Androic, D.;Armstrong, D.S.;Asaturyan, A;Bartlett, K.;Beaufait, J.;Beminiwattha, R.S.;Benesch, J.;Benmokhtar, F.;Birchall, J.;Carlini, R.D.
• 通讯作者: Carlini, R.D.

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

Parity-violating inelastic electron-proton scattering at low Q2 above the resonance region

谐振区上方低 Q2 处的宇称破坏非弹性电子-质子散射

• DOI: 10.1103/physrevc.101.055503
• 发表时间: 2020
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: Androić, D.;Armstrong, D. S.;Asaturyan, A.;Bartlett, K.;Beminiwattha, R. S.;Benesch, J.;Benmokhtar, F.;Birchall, J.;Carlini, R. D.;Cornejo, J. C.
• 通讯作者: Cornejo, J. C.

Determination of the Al27 Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement

通过宇称破坏电子散射测量确定 Al27 中子分布半径

• DOI: 10.1103/physrevlett.128.132501
• 发表时间: 2022
• 期刊: Physical Review Letters
• 影响因子: 8.6
• 作者: Androić, D.;Armstrong, D. S.;Bartlett, K.;Beminiwattha, R. S.;Benesch, J.;Benmokhtar, F.;Birchall, J.;Carlini, R. D.;Cornejo, J. C.;Covrig Dusa, S.
• 通讯作者: Covrig Dusa, S.

Determination of the Proton's Weak Charge and Its Constraints on the Standard Model

质子弱电荷的确定及其对标准模型的约束

• DOI: 10.1146/annurev-nucl-101918-023633
• 发表时间: 2019
• 期刊: Annual Review of Nuclear and Particle Science
• 影响因子: 12.4
• 作者: Carlini, Roger D.;van Oers, Willem T.H.;Pitt, Mark L.;Smith, Gregory R.
• 通讯作者: Smith, Gregory R.