Precision Measurements in Intermediate Energy Physics

该奖项将支持我们小组在费米国家加速器实验室（Fermilab）领导的两个重大新实验：Mu2e和μ子g-2 （E989）。由米勒（J. Miller）共同领导的费米实验室Mu2e实验将在10^{-16}水平上寻找轻子味违反(LFV) μ子到电子的转换反应，灵敏度是目前极限的1万倍。b·l·罗伯茨是此次μ子g-2实验的共同负责人。这两个实验都涉及到一个偶极算子，并且在超对称的背景下，探测了那个特殊的超越sm （BSM）理论的互补方面。Mu2e对更大范围的物理敏感，比正μ子到光子和正电子的LFV衰变更敏感，后者必须经过偶极子相互作用。μ子异常磁矩（g-2）也对大范围的BSM物理敏感。这是一种手性变化的、风味对角线相互作用，它可能来自超对称性中的电荷和中性子，或者来自隐藏U(1)扇区的“暗光子”，或者来自Randall-Sundrum模型。目前，SM和布鲁克海文实验之间的差异约为3.5个标准差。费米实验室E989的设计跨越了5个标准偏差阈值。无论费米实验室E989的结果如何，它都将为解释大型强子对撞机发现的新现象提供重要的约束。MuSun实验正在测量氘上介子捕获的弱矩阵元素，这与为太阳提供动力的弱pp聚变矩阵元素有关。这个奖项将支持我们小组在费米国家加速器实验室（Fermilab）领导的两个重大新实验：Mu2e和μ子g-2。它还将支持我们参加另外两个实验：瑞士保罗谢勒研究所的MuSun实验和橡树岭国家实验室正在准备的中子电偶极矩（EDM）实验。米勒（J. Miller）是费米实验室Mu2e实验的共同负责人，该实验将寻找μ子在不发射中微子的情况下转化为电子的过程。b·l·罗伯茨是费米实验室μ子g-2实验的共同负责人，该实验将比布鲁克海文国家实验室之前的实验精确四倍地测量与μ子相关的磁性。这两个实验都在寻找新物理学无法用标准模型解释的证据，标准模型目前描述了粒子物理学中所有测量量，但众所周知是不完整的。先前g-2实验的结果显示了一些新的线索，这应该由费米实验室的实验来澄清。这个项目是对瑞士日内瓦大型强子对撞机能量前沿搜索的补充。R. Carey正在进行MuSun实验，该实验测量负介子捕获氘核（由质子和中子组成）并通过将质子变为中子将其分解的速率。这个过程很有趣，因为它可能与两个质子融合形成氘有关，即“氢的燃烧”，为太阳提供能量。

This award will support our group's leadership of two major new experiments at the Fermi National Accelerator Laboratory (Fermilab): Mu2e, and muon g-2 (E989). The Mu2e experiment at Fermilab, co-led by J. Miller will search for the lepton flavor violating (LFV) muon to electron conversion reaction at the 10^{-16} level, a factor of 10,000 times more sensitive than the present limit. B.L. Roberts is co-leading the muon g-2 experiment. Both experiments involve a dipole operator, and in the context of supersymmetry probe complementary aspects of that particular beyond-the-SM (BSM) theory. Mu2e is sensitive to a wider range of physics than the LFV decay of the positive muon to a photon and positron, which must go through the dipole interaction. The muon anomalous magnetic moment (g-2) is also sensitive to a wide range of BSM physics. It is a chiral-changing, flavor-diagonal interaction, which could have contributions from the chargino and neutralino in SUSY, or the "dark photon" from a hidden U(1) sector, or from Randall-Sundrum models. At present the difference between the SM and the Brookhaven experiment is around 3.5 standard deviations. Fermilab E989 is designed to cross the five standard deviation threshold. Whatever the result from Fermilab E989, it will provide an important constraint on the interpretation of new phenomena found at the LHC. The MuSun experiment is measuring the weak matrix element for muon capture on deuterium, which is related to the weak pp fusion matrix element that powers the sun.This award will support our group's leadership of two major new experiments at the Fermi National Accelerator Laboratory (Fermilab): Mu2e and muon g-2. It will also support our participation in two other experiments: the MuSun experiment at the Paul Scherrer Institute in Switzerland and the neutron electric dipole moment (EDM) experiment being prepared for Oak Ridge National Laboratory. J. Miller is co-leading the Fermilab Mu2e experiment that will search for the conversion of a muon into an electron without the emission of neutrinos. B.L. Roberts is co-leading the Fermilab muon g-2 experiment which will measure the magnetism associated with the muon a factor of four times more precisely than the previous experiment at the Brookhaven National Laboratory. Both of these experiments are looking for evidence of New Physics that cannot be explained by the Standard Model, a theory that at present describes all measured quantities in particle physics, but is known to be incomplete. Results from the previous g-2 experiment show a hint of something new, which should be clarified by the Fermilab experiment. This program is complementary to the searches at the energy frontier at the Large Hadron Collider in Geneva Switzerland. R. Carey is working on the MuSun experiment, which measures the rate at which a negative muon captures on the deuterium nucleus (made up of a proton and neutron), and breaks it apart by changing the proton into a neutron. This process is interesting since it can be related to the fusion of two protons together to form deuterium, the "burning of hydrogen" that powers the sun.