Investigating Nucleon Structure and Phenomena Beyond the Standard Model

尽管粒子物理标准模型取得了许多成功，但众所周知，它是不完整的，这意味着在更远的地方存在着重要的物理学。例如，有来自天文观测的强有力的证据表明存在所谓的暗物质。标准模型的已知粒子只占宇宙中总物质的一小部分。人们对暗物质的本质知之甚少。许多实验正在进行中或处于计划阶段，以寻找在一种新型粒子中表现出来的暗物质。杰斐逊实验室已经提出了一项技术要求很高的实验，名为暗光，目的是专门研究电子与质子散射过程中所谓的暗光子的产生。如果这样的粒子存在，它将导致超越标准模型的新物理，因此将改变我们对宇宙物质分布的理解。这笔赠款是为了研究暗光第一阶段轻子跟踪器，将作为一套气体电子倍增(GEM)探测器建造，这是一项相对较新的技术，该小组近年来在奥林巴斯和缪斯项目的参与下开发了专业知识。美国国家科学基金会通过重大研究仪器(MRI)拨款资助了暗光一期设备，该实验预计将于2016-2017年在杰斐逊实验室进行。该奖项支持一名研究生攻读该项目的博士学位。博士论文的一部分将重点介绍轻子跟踪器在暗光一期设备中的构建和实施。论文的第二个重点将是暗光第一阶段数据的运行、模拟和分析，有三个独特的科学目标：1)利用杰斐逊实验室的能量回收直线加速器进行研究，2)测量暗光中的标准模型过程，以及3)寻找一种名为A‘的新粒子。

Despite its numerous successes the Standard Model of Particle Physics is known to be incomplete, implying that there exists important physics beyond. As an example, there is strong evidence from astronomical observations for the existence of so-called dark matter. The known particles of the Standard Model make up only a small fraction of the total matter in the Universe. Very little is known about the nature of dark matter. A number of experiments are underway or in the planning stage to look for dark matter manifesting itself in a new type of particle. A technically demanding experiment at Jefferson Lab, called DarkLight, has been proposed to specifically search for the production of a so-called dark photon in the scattering of electrons from protons. If such a particle were to exist, it would lead to new physics beyond the Standard Model, and hence would be transformative in our understanding of the matter distribution of the Universe.This grant is for work on the DarkLight phase I lepton tracker, to be built as a set of Gas Electron Multiplier (GEM) detectors, a relatively new technology for which the group has developed expertise in recent years with the involvement in the OLYMPUS and MUSE projects. The NSF funded the DarkLight phase-I apparatus through a Major Research Instrumentation (MRI) grant, and the experiment is expected to take place at Jefferson Lab in 2016-2017. This award provides support for one graduate student to pursue a PhD on this project. One part of the PhD thesis will have a hardware focus with the construction and implementation of the lepton tracker into the DarkLight phase I apparatus. The second focus of the thesis will be the running, simulation and analysis of DarkLight phase I data, with three distinctive scientific goals: 1) studies with the Energy Recovery Linac at Jefferson Lab, 2) measurement of Standard Model processes in DarkLight, and 3) search for a new particle called the A'.