Electron

Dark matter

Optics

Astrophysics

Quantum mechanics

Condensed matter physics

Nuclear physics

Dielectric

Scattering

Dielectric function

Physics

Electron scattering

Physical Review Letters

We show that the rate for dark-matter--electron scattering in an arbitrary material is determined by an experimentally measurable quantity, the complex dielectric function, for any dark matter interaction that couples to electron density. This formulation automatically includes many-body effects, eliminates all systematic theoretical uncertainties on the electronic wave functions, and allows a direct calibration of the spectrum by electromagnetic probes such as infrared spectroscopy, x-ray scattering, and electron energy-loss spectroscopy. Our formalism applies for several common benchmark models, including spin-independent interactions through scalar and vector mediators of arbitrary mass. We discuss the consequences for standard semiconductor and superconductor targets and find that the true reach of superconductor detectors for light mediators exceeds previous estimates by several orders of magnitude, with further enhancements possible due to the low-energy tail of the plasmon. Using a heavy-fermion superc...

Determining Dark-Matter–Electron Scattering Rates from the Dielectric Function