NMR Search for the Dark-Matter Wind

该项目的目标是开创一个实验框架，使广泛的系统搜索轻粒子，包括难以捉摸的轴子粒子，理论上最有动机的候选人之一的暗物质。暗物质的性质是现代物理学的中心开放问题之一。阐明暗物质的粒子性质的发现将为从粒子物理学到天体物理学和宇宙学的广泛领域开辟新的前景，并将为标准模型之外的物理学提供独特的见解。在暗物质的候选者中，两种截然不同的粒子脱颖而出，因为它们来自全面的理论框架，但都没有在实验中观察到。一种是被称为弱相互作用大质量粒子（WIMP）的重粒子。各种实验的结果限制了它的质量和耦合。另一种是轴子，一种轻标量粒子。到目前为止，只有一个实验探测轴子暗物质，只有一小部分的允许质量。在这里，我们提出了一个新的方向，在实验上寻找轴子和轴子类粒子（ALP）。我们将使用核磁共振（NMR）技术来检测由光粒子场的空间涨落与原子核自旋耦合引起的自旋进动。这种方法涵盖了轴子和ALP的参数空间的大部分，许多数量级超出了目前的限制，从而建立了一个高灵敏度的搜索广泛的暗物质候选人和通用的轻粒子。

The goal of this project is to pioneer an experimental framework that enables broad systematic searches for light particles, including the elusive axion particle, one of the theoretically best-motivated candidates for dark matter.The nature of dark matter is one of the central open problems in modern physics. A discovery elucidating the particle nature of dark matter would open up new vistas for a wide range of areas, from particle physics to astrophysics and cosmology, and would provide unique insights into the physics beyond the Standard Model. Among the candidates proposed for dark matter, two distinctly different particles stand out as they arise from comprehensive theoretical frameworks, but neither has been observed experimentally. One is a heavy particle known as weakly interacting massive particle (WIMP). Null results from a variety of experiments constrain its mass and coupling. The other is the axion, a light scalar particle. So far, just one experiment probes axion dark matter, and only over a fraction of the allowed masses.Here, we propose a new direction in the experimental search for axion and axion-like paticles (ALPs). We will use nuclear magnetic resonance (NMR) techniques for detecting spin precession caused by the coupling of spatial fluctuations in light-particle fields to the spin of nuclei. This approach covers large parts of the parameter space of axions and ALPs, many orders of magnitude beyond current constraints, thus establishing a highly sensitive search for a broad class of dark-matter candidates and for generic light particles.