Intermediate Energy Physics at Boston University

我们在波士顿大学的中间能源研究小组由三名教师，两名博士后，四名研究生和几名兼职本科生组成。在未来三年内，我们将：1）继续开展Muon g-2实验。μ介子就像一个重电子，但不稳定，像放射性核同位素一样衰变。因为它既有自旋又有电荷，所以它的行为就像一个微观的条形磁铁，我们在实验（g-2）中测量了它的磁性。我们的最新值，基于我们的一小部分数据，与标准模型（一种描述自然界中粒子和它们之间作用力的理论）的预测有几倍的误差。如果在我们分析了所有的数据之后，这种分歧仍然存在，那将是非常令人兴奋的，因为它表明了标准模型之外的新物理学的存在。我们还计划了另外两个实验，使用与g-2相同的大型储存环磁体，测量μ子电偶极矩（EDM）和直接测量μ子中微子质量。理论上EDM预计比我们可以测量的要小，而其他实验的间接测量表明中微子质量不为零。2）测量μ子寿命，它决定了标准模型中弱相互作用的强度。3）测量μ子到电子的转换率，达到前所未有的精度，这是标准模型所禁止的过程。所有这些测量都直接测试标准模型。实验值与理论值的任何重大偏差都暗示着存在着超出我们已知范围的物理学。

Our Intermediate Energy research group at Boston University consists of threefaculty, two postdoctoral fellows, four graduate students, and severalpart-time undergraduate students. In the next three years, we will:1) Continue to work on the Muon g-2 experiment. The muon is likea heavy electron but is unstable and decays like a radioactive nuclearisotope. Because it has both spin and charge, it behaves like a microscopicbar magnet, whose magnetism we measure in our experiment (g-2). Our latestvalue, based on a small part of our data, disagrees with the Standard Model(a theory which describes the particles in nature and the forces between them)prediction by several times the error. If this disagreement persists afterwe analyze all of our data, it will be very exciting since it suggests theexistence of new physics beyond the standard model. We plan two otherexperiments using the same large storage ring magnet which is used forg-2, the measurement of the muon electric dipole moment(EDM) and thedirect measurement of the muon neutrino mass. The EDM is expected intheory to be smaller than we can measure, while indirect measurementsfrom other experiments suggest that the neutrino mass is not zero.2) Measure the muon lifetime, which determines the strength of theweak interaction within the standard model.3) Measure the muon to electron conversion rate to unprecedented accuracy,a process which is forbidden by the Standard Model.All of these measurements directly test the Standard Model. Anysignificant deviation of the experimental values from theory would implythat there is physics beyond what we already know.