RUI: Searching for Preferred Directions in Space and Time

将进行两个实验，以检验自然基本的基本对称性。这些实验中的第一个将在宇宙中寻找首选的方向。这是通过精确测量水星核的能量来实现的，它是水星核自转相对于固定恒星排列的函数。这种优先空间方向的存在违反了局部洛伦兹不变性(LLI)原理，LLI是当前大多数物理理论的基本对称性之一。第二个实验使用一种名为格拉铁石榴石的陶瓷材料来寻找电子的永久电偶极矩(EDM)。这是解决物理学中最大的实验挑战之一的一种新方法。基本粒子的非零电火花加工的存在违反了时间反转不变性原理。观察到对上述任何一种自然对称性的违反，都会从根本上改变我们对物理世界的理解。弦理论和超对称性仍然是粒子物理学中最有吸引力的两个理论，尽管事实证明这两个理论都很难检验。有人提出，弦理论可能允许在接近LLI实验中将要探索的水平上违反局部洛伦兹不变性。同样，超对称性预测的电子电偶极矩非常接近在EDM搜索中将被探测的水平。LLI实验可能会导致精密光泵磁力计的进一步改进。电火花加工实验将扩大我们对铁石榴石表面电磁相互作用的理解。这一改进的理解在未来的磁信息存储设备中可能很重要。这两个实验都将为本科生提供有价值的培训。

Two experiments will be pursued that test the fundamental underlying symmetries of nature. The first of these experiments will look for a preferred direction in the universe. This is accomplished by precisely measuring the energy of a mercury nucleus as a function of the alignment of its spin with respect to the fixed stars. The existence of such a preferred spatial direction violates the principle of Local Lorentz Invariance (LLI), one of the underlying symmetries of most current physical theories. The second experiment searches for a permanent electric dipole moment (edm) of the electron using a ceramic material called gadolinium iron garnet. This is a novel approach to one of the greatest experimental challenges in physics. The existence of a non-zero edm of a fundamental particle would violate the principle of time-reversal invariance. Observation of a violation of either of the above symmetries of nature would radically alter our understanding of the physical world. String theory and supersymmetry remain two of the most attractive theories in particle physics, though both have proven to be very difficult to test. It has been suggested that string theory might allow for a violation of local Lorentz invariance at a level close to that which will be probed in the LLI experiment. Similarly, supersymmetry predicts an electron electric dipole moment very close to the level that will be probed in the edm search. The LLI experiment may result in further improvements in precise optically pumped magnetometers. The edm experiment will stretch our understanding of electromagnetic interactions at the surfaces of the iron garnets. This improved understanding might be important in future magnetic information storage devices. Both of these experiments will provide valuable training to undergraduates.