RUI: Searching for Preferred Directions in Space and Time

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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.