Precision Measurements of Parity Violation in Nucleon-Nucleon and Electron-Proton Scattering

该奖项支持测量质子弱电荷的研究，然后使用该测量来研究基本物质和相互作用标准模型的新方面。标准模型以优雅的方式描述了自然界四种力中的三种;这三种力是电磁相互作用，弱相互作用和强相互作用。质子的弱电荷是一个基本性质，就像它的电荷和质量一样，决定了质子对弱相互作用的响应。它还与弱相互作用和电磁相互作用如何相互混合有关。由于标准模型对混合如何随相互作用中交换的动量而变化做出了明确的预测，只有一组非常精确的测量存在于非常高的动量转移值，因此在动量转移值较低时对质子弱电荷的精确测量是标准模型的严格测试。此外，它对标准模型中尚未包含的物理现象非常敏感。JLab的Qweak实验将通过散射质子中的极化电子并测量它们散射的速率来进行这种精确测量。从这种散射中提取质子的弱电荷需要用专门的设备进行精密的校准。该奖项支持的研究小组将委托探测器触发校准阶段的所有其他探测器，并开发将在校准阶段使用的电子设备。硬件和软件问题都将在这个项目中得到解决，使学生和博士后研究人员将获得广泛的宝贵技能。 该奖项还支持扩大代表性不足的群体参与物理学的计划。

This award supports research to measure the weak charge of the proton and then use that measurement to investigate new aspects of the Standard Model of fundamental matter and interactions. The Standard Model describes three of the four forces of nature in an elegant manner; those three forces are the electromagnetic interaction, the weak interaction, and the strong interaction. The weak charge of the proton is a basic property, like its electric charge and mass, that determines the proton's response to the weak interaction. It is also related to how the weak and electromagnetic interactions mix with each other. Because the Standard Model makes well defined predictions of how that mixing varies with the amount of momentum that is exchanged in an interaction, with only one set of very precise measurements existing at very high values of momentum transfer, a precise measurement of the proton's weak charge at a low value of momentum transfer is a rigorous test of the Standard Model. Additionally, it is sensitive to physics not yet included in the Standard Model.The Qweak experiment at JLab will carry out this precise measurement by scattering polarized electrons from protons and measuring the rate at which they scatter. Extracting the weak charge of the proton from this scattering will require delicate calibrations with specialized equipment. The research group supported by this award will commission the detector that will trigger all other detectors of the calibration phase, and develop the electronics that will be used during the calibration phase. Both hardware and software issues will be addressed in this project so the students and postdoctoral researchers will gain a wide range of valuable skills. Programs to broaden participation of under-represented groups in physics are also supported by this award.