RUI: Searching for Preferred Directions in Space and Time

将进行两个实验来测试自然界的基本对称性。这些实验中的第一个将在宇宙中寻找一个首选方向。这是通过精确测量水星核的能量，作为它的自旋与固定恒星的对齐的函数来完成的。这种优先空间方向的存在违反了局部洛伦兹不变性原理（LLI），这是当前大多数物理理论的基本对称性之一。第二个实验用一种叫做钆铁石榴石的陶瓷材料寻找电子的永久电偶极矩。这是一种新颖的方法来解决物理学中最大的实验挑战之一。一个基本粒子的非零edm的存在将违反时间反转不变性原理。观察到违反上述任何一种自然对称性都将从根本上改变我们对物理世界的理解。弦理论和超对称理论仍然是粒子物理学中最具吸引力的两个理论，尽管它们都被证明是非常难以检验的。有人提出，弦理论可能允许局部洛伦兹不变性在接近LLI实验的水平上被破坏。类似地，超对称预测了一个电子电偶极矩，非常接近在电火花搜索中探测到的水平。LLI实验可能会导致精密光泵磁力仪的进一步改进。电火花加工实验将扩展我们对铁石榴石表面电磁相互作用的理解。这种改进的理解可能对未来的磁性信息存储设备很重要。这两个实验都将为本科生提供有价值的训练。

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.