Probing PeV-scale new physics using the electron electric dipole moment

宇宙中物质比反物质多得令人困惑，这是我们这个时代最大的谜团之一。这个难题的解决方案要求基本的时间反演对称性被破坏的程度比粒子物理学标准模型中可能的程度要大得多，这表明未被发现的新物理学可能是我们宇宙这种基本性质的原因。发现新物理学线索的一个强有力的方法是以超高精度搜索基本粒子（如电子）的永久电偶极矩。我们正在建立一个电子电偶极矩（eEDM）搜索实验，可以提高超过4个数量级的当前最佳测量。 如此大的精度飞跃需要一种全新的技术。特别是，与以前的所有其他努力相比，需要精确测量的电子数量要多得多。我们已经开发出一种新的方法来执行eEDM搜索使用一个大的合奏极性分子被困在稀有气体晶体。极性分子中的电子由于分子结构而经历极大的电场。稀有气体晶体的晶格固定了分子的方向和位置：以这种方式捕获分子可以提高实验的测量时间（从而提高精度），但也可以冻结分子运动并消除对外部施加电场的需要，从而消除许多类型的潜在系统误差。稀有气体固体中的定向分子系综也自然配备了出色的共磁强计，以抑制磁场波动引起的误差，从而实现高精度的eEDM实验。所有这些特征导致eEDM实验具有高达极高能量尺度的新物理灵敏度。本实验将由EDMCubed协作组（多伦多大学、约克大学、密歇根州立大学）使用位于约克大学的装置进行。 精确的eEDM测量是对发现新物理的对撞机实验的一种独立于模型的非常重要的补充。这是加拿大的第一次此类努力，我们的目标是实现对新物理学的灵敏度，这比任何其他当前或拟议的实验都要高出许多数量级。该实验将使加拿大亚原子物理界在高能物理的精确前沿处于世界领先地位，并培养新一代的亚原子物理学家。

The bewildering excess of matter over antimatter in the universe is one of the biggest puzzles of our time. The proposed solutions to this puzzle require that fundamental time-reversal symmetry is violated to a much larger extent than is possible within the Standard Model of particle physics, suggesting that undiscovered new physics could be responsible for such a basic property of our universe. A powerful way to discover hints of new physics is to search with ultra-high precision for a permanent electric dipole moment of fundamental particles such as electrons. We are building an electron electric dipole moment (eEDM) search experiment that can improve upon the current best measurements by more than 4 orders of magnitude. Such a large leap in precision requires a radical new technique. In particular, compared to all other previous efforts, a much larger number of electrons need to be precisely measured. We have developed a new method to perform an eEDM search using a large ensemble of polar molecules trapped in a rare-gas crystal. Electrons in polar molecules experience extremely large electric fields due to the molecular structure. The lattice of the rare-gas crystal fixes the orientation and position of the molecules: trapping molecules in this way improves the measurement time (and therefore the precision) of the experiment, but also freezes molecular motion and removes the need for an externally applied electric field, thereby eliminating many classes of potential systematic errors. An ensemble of oriented molecules in a rare-gas solid is also naturally equipped with excellent co-magnetometers to suppress errors from magnetic field fluctuations, enabling a high-precision eEDM experiment. All of these features result in an eEDM experiment with new physics sensitivity up to extremely high energy scales. This experiment will be performed by the EDMCubed Collaboration (University of Toronto, York University, Michigan State University) using an apparatus located at York University. Precision eEDM measurements are a model-independent and vitally important complement to collider experiments for discovering new physics. This is the first Canadian effort of its kind, and we aim to achieve a level of sensitivity to new physics that is many orders of magnitude beyond any other current or proposed experiment. This experiment will place the Canadian subatomic physics community in a world leading position at the precision frontier of high energy physics, and train a new generation of subatomic physicists.