SPP 1491: Precision Experiments in Particle- and Astrophysics with Cold and Ultracold Neutrons

这个优先计划希望解决一些现代科学尚未解决的问题：基本力的性质和潜在的对称性，以及非常小距离上引力的性质。新设施和技术的发展为精度的显著提高打开了窗口，比以前的调查提高了一到两个数量级。这允许以一种补充的方式来探索这些问题，以lhc为基础的实验，甚至概述一种独特的方式。该研究计划将集中在与具体物理/天体物理问题直接相关的四个优先领域：优先领域A: cp对称性违反和早期宇宙中的粒子物理（主要通过寻找中子电偶极矩来解决）；优先领域B：弱相互作用的结构和性质以及标准模型的可能扩展（主要通过对中子衰变的精确研究来解决）；优先领域C：引力与量子理论的关系（通过对引力场中低能束缚态的研究来探讨）；优先领域D：电荷量子化和中子的电中性（通过对中子电荷的精确测试来探测）。实验精度的预期提高必须与新的或改进的测量技术的发展同时进行，而这些技术往往处于可行性的极端边缘。目前，各个研究中心正在准备新的强大的超冷中子源。它们将使我们能够对引力和中子的电偶极矩进行高精度的实验。另一方面，中子β衰变研究需要一个非常出色的衰变产物来源，即在冷中子导管内有很大的活性衰变体积。这些测量将使我们能够探索几乎独立于质量尺度（EDM）的新物理学，并了解与宇宙物质-反物质不对称相关的过程中的cp对称性破坏。弱相互作用的结构可以以前所未有的精度进行测试，从而可以在没有直接观察的情况下对新的中间玻色子敏感。因此，今天观察到的自然左撇子的起源可能会被揭示出来。在非常小的距离上对牛顿定律的精确研究，反过来又允许在微米水平上探测额外的维度，并可以揭示在其中作用的新规范玻色子的存在。这再次暗示了宇宙早期的时空结构，并且与宇宙膨胀阶段额外空间维度的卷曲有关。

This Priority Programme wants to address some of the unsolved questions of modern science: the nature of the fundamental forces and underlying symmetries, as well as the nature of the gravitational force at very small distances. New facilities and technological developments now open the window for significant improvement in precision by one to two orders of magnitude over previous investigations. This allows to probe these questions in a complementary way to LHC-based experiments or even outline a unique way. The research programme will focus on four Priority Areas, which are directly related to specific physics/astrophysics issues: Priority Area A: CP-symmetry violation and particle physics in the early universe (addressed mainly by the search for the neutron electric dipole moment); Priority Area B: the structure and nature of weak interaction and possible extensions of the standard model (addressed mainly by precise studies of the neutron beta decay); Priority Area C: relation between gravitation and quantum theory (probed by investigations of low-energy bound states in the gravitational field); Priority Area D: charge quantisation and the electric neutrality of the neutron (probed by a precision test of the neutrons electric charge).The intended improvement in experimental precision has to go in parallel with the development of new or improved measurement techniques, which are often at the extreme border of feasibility. Novel powerful sources for ultracold neutrons are presently being prepared at various research centres. They will allow us to perform high-precision experiments on gravitation and the electric dipole moment of the neutron. On the other hand, neutron beta decay studies require a very brilliant source of decay products, i.e., a large active decay volume inside a cold neutron guide. These measurements should enable us to probe new physics almost independent of the mass scale (EDM) and to understand CP-symmetry violation in processes relevant to the matter-antimatter asymmetry of the universe. The structure of weak interaction can be tested with unprecedented precision, making possible to be sensitive to new intermediate bosons without direct observation. Thus, the origin of natures left-handedness observed today may be revealed. Precision studies of Newtons law at very small distances in turn allow to probe for extra dimensions at the µm level and can reveal the existence of new gauge bosons acting within. This again could hint to the space-time structure at very early times of the universe and is related to the curling up of extra space dimensions in the inflationary phase of the universe.