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

宇宙中物质多于反物质的现象令人困惑，这是我们这个时代最大的谜团之一。这个谜题的解决方案要求基本的时间反转对称性被违反的程度远远超过粒子物理标准模型的可能程度，这表明未被发现的新物理可能是我们宇宙的这种基本特性的原因。发现新物理学线索的一个有力方法是用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，可以将目前最好的测量结果提高4个数量级以上。如此大的精度飞跃需要一种全新的技术。特别是，与之前的所有努力相比，需要精确测量的电子数量要多得多。我们已经开发了一种新的方法，利用捕获在稀有气体晶体中的极性分子的大集合来执行eEDM搜索。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改善实验的测量时间（从而提高精度），但也冻结了分子运动并消除了对外部施加电场的需要，从而消除了许多类型的潜在系统误差。稀有气体固体中的定向分子集合也自然配备了优秀的共磁仪，以抑制磁场波动带来的误差，从而实现高精度的eEDM实验。所有这些特征都使eEDM实验具有新的物理灵敏度，可以达到极高的能量尺度。该实验将由edmcube协作（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设备进行。精确的edm测量是一种独立于模型的，对发现新物理的对撞机实验至关重要的补充。这是加拿大在这方面的第一次努力，我们的目标是达到对新物理学的敏感度水平，这比任何其他当前或拟议的实验都要高许多个数量级。这个实验将使加拿大亚原子物理界在高能物理的精密前沿处于世界领先地位，并培养新一代亚原子物理学家。

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.