Ultracold eEDM: a new experiment to measure the electron's electric dipole moment using ultracold moelcules

可见宇宙几乎不包含任何反物质，但包含大量物质。已知的基本力几乎不区分物质和反物质，所以一定有未被发现的力可以解释这种不对称性。这些新的作用力肯定会影响基本粒子的形状，使它们变得略微非球面。测量这种扭曲--称为电偶极子--将揭示新力量的存在和性质。到目前为止，测量只探测到了球形粒子，表明它们的电偶极子非常小。我们的目标是通过测量电偶极子与外加电场的微小相互作用能来确定电子的形状。当电子被束缚在极性分子中时，这种能量就会增强，这是一种狭义相对论的效应。我们将使用一种增强因子为一百万的氟化Yb分子气体，冷却到50微开尔文的温度。这种深度冷却是一项新的技术进步，将使我们的测量比以前的实验灵敏度高数百倍。我们将对远远超出大型强子对撞机能量范围的基本力敏感，但我们不需要粒子对撞机--实验将在伦敦的一个小实验室进行。在头两年，我们将设计和制造进行测量所需的仪器。然后我们将对装置的每个部分进行优化，并证明它对预期水平的电子形状是敏感的。最后，我们将调查实验中潜在的系统误差--可能模仿电偶极子特征的效应--并消除这些误差，以完善实验。

The visible Universe contains hardly any antimatter, but plenty of matter. The known fundamental forces barely distinguish between matter and antimatter so there must be undiscovered forces that account for this asymmetry. These new forces must influence the shapes of the fundamental particles, making them slightly aspherical. Measuring this distortion - known as the electric dipole - will reveal the existence and nature of the new forces. So far, measurements have detected only spherical particles, showing that their electric dipoles are exceedingly small. We aim to determine the shape of the electron by measuring the tiny interaction energy of the electric dipole with an applied electric field. This energy is enhanced when the electron is bound up in a polar molecule, an effect of special relativity. We will use a gas of ytterbium fluoride molecules, whose enhancement factor is a million, cooled to a temperature of 50 microkelvin. This deep cooling is a new technological advance that will make our measurement hundreds of times more sensitive than previous experiments. We will be sensitive to fundamental forces lying far beyond the energy range of the Large Hadron Collider, but we will not need a particle collider - the experiment will be done in a small laboratory in London. In the first two years, we will design and build the apparatus needed to make the measurement. Then we will optimize each part of the apparatus, and demonstrate that it is sensitive to the shape of the electron at the anticipated level. Finally, we will investigate potential systematic errors in the experiment - effects that might mimic the signature of an electric dipole - and eliminate these errors so that the experiment is perfected.