RUI: Testing Fundamental Symmetries with Muon Experiments

这一奖项将支持雷吉斯大学团队继续探索与亚原子物理标准模型之间为数不多的已知实验差异之一，该标准模型编码了我们对物质和能量的基本构件的理解。费米实验室的Muon g-2实验观测到了Muon，这是一种亚原子粒子，类似于大质量电子，当它们通过磁场时。它测量了介子的自旋方向旋转的速度；这个速度是由所有类型的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种类的力。标准模型做出了精确的理论预测；它与最近公布的实验第一年数据收集的结果不同，在一定程度上可能揭示新的物理过程的影响。已经收集了更大的数据集，并正在进行分析，预计还需要一年的数据收集时间。与此同时，标准模型预测的精度主要受到强子贡献的不确定性的限制：强子是由夸克和胶子组成的粒子，这是核物理学的领域。REGIS小组将在很大程度上参与费米实验室实验的完成和欧洲核子研究中心MUonE实验的发展，该实验将用一种独立的方法测量强子贡献。里吉斯大学的物理课程以本科生为重点，这一奖项将为物理学专业的学生和未成年人创造机会，让他们参与到核物理的前沿研究中来。他们将在参与Muon g-2和MUonE实验的同时发展实验室、数据分析和计算技能，并得到大量指导。此外，里吉斯大学是一个多元化的校园，因此许多将得到这笔续期拨款支持的学生预计将来自目前科学界代表性不足的群体。Muon g-2实验将把测量Muon的异常磁矩的精度从350ppb提高到140ppb，为发现提供了一个窗口。按照计划，将实验扩展到最后一次运行中的负Muon极性，也将允许对CPT和Lorentz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，很快将成为解释Muon 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将根据介子束与目标电子的弹性散射中电磁耦合(α)与能量尺度的运行来确定该分量。里吉斯大学的研究小组将继续操作和分析Muon g-2实验中“光纤竖琴”光束监测探测器的数据，并进一步开发合作的蒙特卡罗模拟，用于研究与存储的Muon光束的动态运动有关的问题。REGIS小组还将为完成MUonE实验的技术方案和其第一次物理数据收集做出贡献，最初将在电磁量热计和其他下游探测器组件的设计、模拟和测试中发挥作用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.