A subtle quantum shake called the Migdal effect allows us to see dark matter particles that are thousands of times lighter than we expected.
Most dark matter detectors are built to find heavy particles, leaving anything lighter than an atom completely invisible. This research uses electron excitations caused by a nuclear recoil to detect particles as light as a few MeV. This effectively opens a new window into a light dark matter world that was previously considered unreachable. By looking for these tiny electrical signals, we can test theories that were once untestable. It dramatically expands the territory where we might finally find the universe's missing mass.
Probing Sub-GeV Dark Matter via Migdal Effect-Induced Electron Excitations
arXiv · 2604.26773
The electron ionization predicted by the Migdal effect in dark matter-nucleus scattering enhances experimental sensitivity to sub-GeV dark matter. In this work, we demonstrate that lower-energy electron excitations provide a novel and promising pathway, enabling the detection of even lighter dark matter particles previously considered inaccessible for direct searches. Direct detection experiments employing a superfluid $^4$He target can exploit this channel by observing electronic excitations vi