Magnetic monopoles have long been predicted in theory and could exist as a stable object in our universe. As they move around in galaxies, magnetic monopoles could be captured by astrophysical objects like stars and planets. Here, we provide a novel method to search for magnetic monopoles by detecting the monopole moment of the Earth's magnetic field. Using over six years of public geomagnetic field data obtained by the Swarm satellites, we apply Gauss's law to measure the total magnetic flux, which is proportional to the total magnetic charge inside the Earth. To account for the secular variation of satellite altitudes, we define an altitude-rescaled magnetic flux to reduce the dominant magnetic dipole contribution. The measured magnetic flux is consistent with the existing magnetic field model that does not contain a monopole moment term. We therefore set an upper limit on the magnetic field strength at Earth's surface from magnetic monopoles to be $|B_{\rm m}| < 0.13$ nT at 95% confidence level, which is less than $2\times 10^{-6}$ of Earth's magnetic field strength. This constrains the abundance of magnetically-charged objects, including magnetic black holes with large magnetic charges.
Searching for cavities of various densities in the Earth's crust with a low-energy electron-antineutrino beta-beam
我们建议使用长基线电子-反中微子消失实验来寻找地壳中不同密度的深地下洞穴，该实验通过具有高度增强的光度的低能β束来实现。我们关注四个案例：密度接近于水的空洞、铁条带状构造、较重的矿床以及被认为在强烈地震发生前出现的异常电荷聚集区。识别空洞的灵敏度达到的置信水平高于$3σ$和$5σ$的曝光时间分别为3个月和1.5年，空洞密度低于1克厘米$^{-3}$或高于5克厘米$^{-3}$，宽度大于200公里。我们重建的空腔密度，宽度和位置，假设其中一个已知，而保持其他两个自由。我们得到大的允许区域，提高腔密度不同，从地球的平均密度。此外，我们证明，知识的空腔密度是重要的，以获得O（10%）的误差的宽度。最后，我们引入了一个通过改变电子反中微子束的方向来量化腔的存在的可观测量，利用它我们能够识别出在$2σ$到$5σ$ C. L.处的腔的存在。
Searching for dark photon dark matter from terrestrial magnetic fields
Kyoto University（京都大学）；Hiroshima University（广岛大学）；Yukawa Institute for Theoretical Physics, Kyoto University（京都大学汤川理论物理研究所）；Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, The University of Tokyo（东京大学前缘研究机构 Kavli宇宙物理数学研究所）；Korea Institute for Advanced Study（韩国高等研究院）；College of Industrial Technology, Nihon University（日本大学生命理工学院）
Low-Mass Magnetic Monopoles in the Galaxy: Simulations and Comparison with Ultra-High-Energy Cosmic-Ray Data
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Institute of Theoretical Physics, Faculty of Physics, University of Warsaw（华沙大学物理学院理论物理研究所）
Momentum and Matter Matter for Axion Dark Matter Matters on Earth
University of Maryland, College Park（马里兰大学帕克分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Berkeley Center for Theoretical Physics, University of California, Berkeley（加州大学伯克利分校理论物理中心）；Université de Strasbourg（斯特拉斯堡大学）；CNRS（法国国家科学研究中心）；IPHC UMR7178（高能物理研究所）；Université de Genève（日内瓦大学）；Weizmann Institute of Science（魏茨曼科学研究所）；The University of Sydney（悉尼大学）
