RUI: Testing Fundamental Symmetries with Muon Experiments

这个奖项将支持里吉斯大学的研究小组继续探索与亚原子物理学标准模型之间为数不多的已知实验差异之一，该模型编码了我们对物质和能量基本组成部分的理解。费米实验室的μ子g-2实验观察到μ子是一种亚原子粒子，就像大质量的电子一样，当它们穿过磁场时。它测量介子自旋方向旋转的速率；这个速率是由各种介子相互作用的总和决定的，可能包括与新粒子的相互作用，或者通过尚未直接发现的新力的相互作用。标准模型做出了精确的理论预测；它与最近发表的实验第一年数据收集的结果不同，可能会揭示新的物理过程的影响。更大的数据集已经收集并正在分析中，预计还将再收集一年的数据。与此同时，标准模型预测的精度主要受到强子对其贡献的不确定性的限制。强子是由夸克和胶子组成的粒子，属于核物理领域。里吉斯小组将大量参与完成费米实验室的实验，并在欧洲核子研究中心开发MUonE实验，后者将用一种独立的方法测量强子的贡献。里吉斯大学的物理项目以本科生为重点，该奖项将为物理专业的学生和未成年人提供参与核物理前沿研究的机会。他们将在大量指导下参与μ子g-2和μ子one实验，从而发展实验室、数据分析和计算技能。此外，里吉斯大学是一个多元化的校园，因此，许多将得到这项新拨款支持的学生预计将来自目前在科学领域代表性不足的群体。μ子g-2实验将提高μ子异常磁矩的测量精度，从350到140十亿分之一（ppb），为发现提供了一个窗口。按照计划，在最后的运行中将实验扩展到负介子极性，也将允许对CPT和洛伦兹对称性进行精确测试。与标准模型预测相关的不确定性，目前为370 ppb，将很快成为解释μ子g-2结果的限制因素。这种不确定性主要来自强子真空极化分量，MUonE将根据目标电子的介子束弹性散射中具有能量尺度的电磁耦合（α）的运行来确定。里吉斯大学小组将继续操作和分析μ子g-2实验中“光纤竖琴”光束监测探测器的数据，并进一步发展合作的蒙特卡洛模拟，这将用于研究与存储μ子光束动态运动相关的问题。Regis小组还将为完成MUonE实验的技术提案和第一次物理数据收集做出贡献，最初将参与电磁量热计和其他下游探测器组件的设计、模拟和测试。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award will support the Regis University group in continuing to probe one of the few known experimental discrepancies with the Standard Model of subatomic physics, which encodes our understanding of the fundamental building blocks of matter and energy. The Fermilab Muon g-2 experiment observes muons, which are subatomic particles that are like massive electrons, as they move through a magnetic field. It measures the rate at which the muons’ spin directions rotate; this rate is determined by the sum of the muons’ interactions of all kinds, potentially including interactions with new particles or via new kinds of forces that have not yet been discovered directly. The Standard Model makes a precise theoretical prediction; it differs from the recently-published result from the experiment’s first year of data collection at a level that may reveal the effects of new physical processes. A much larger data set has already been collected and is being analyzed, and one additional year of data collection is expected. Meanwhile, the precision of the Standard Model prediction is limited primarily by the uncertainty of the contributions to it from hadrons: particles that are composed of quarks and gluons, which are the domain of nuclear physics. The Regis group will participate substantially both in the completion of the Fermilab experiment and in the development of the MUonE experiment at CERN, which will measure the hadronic contributions with an independent method. Regis University’s physics program is undergraduate-focused, and this award will generate opportunities for physics majors and minors to become involved in leading-edge research in nuclear physics. They will develop laboratory, data analysis, and computing skills as they participate, with substantial mentoring, in the Muon g-2 and MUonE experiments. Furthermore, Regis University is a diverse campus, so many of the students who will be supported by this renewed grant are expected to be from groups that are currently underrepresented in the sciences.The Muon g-2 experiment will improve the precision of the measurement of the muon’s anomalous magnetic moment from 350 to 140 parts per billion (ppb), providing a window for discovery. Extending the experiment to the negative muon polarity in the final run, as is planned, will also allow for a precision test of CPT and Lorentz symmetries. The uncertainty associated with the Standard Model prediction, which is currently 370 ppb, will soon be the limiting factor in interpreting the Muon g-2 result. This uncertainty arises predominantly from the hadronic vacuum polarization component, which MUonE will determine from the running of the electromagnetic coupling (alpha) with energy scale in elastic scattering of a muon beam from target electrons. The Regis University group will continue to operate and analyze data from the “fiber harp” beam monitoring detectors in the Muon g-2 experiment, and to further develop the collaboration’s Monte Carlo simulations, which will be used to study questions related to the dynamic motion of the stored muon beam. The Regis group will also contribute to the completion of the technical proposal for the MUonE experiment and to its first physics data collection, initially taking on roles in the design, simulation, and testing of the electromagnetic calorimeter and other downstream detector components.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.