Dark matter direct detection from the single phonon to the nuclear recoil regime

In most direct detection experiments, the free nuclear recoil description of dark matter scattering breaks down for masses less than or similar to 100 MeV, or when the recoil energy is comparable to a few times the typical phonon energy For dark matter lighter than 1 MeV, scattering via excitation of a single phonon dominates and has been computed previously, but for the intermediate mass range or higher detector thresholds, multiphonon processes dominate. We perform the first calculation of the scattering rate via multiphonon production for the entire keV-GeV dark matter mass range, assuming a harmonic crystal target. We provide an analytic description that connects the single phonon, multiphonon, and the nuclear recoil regimes. Our results are implemented in the public package DARKELF.

Automated summary

This study provides the first calculation of the scattering rate via multiphonon production for the entire keV-GeV dark matter mass range, connecting the single phonon, multiphonon, and nuclear recoil regimes. The results offer important insights into the scattering process of dark matter.