In-medium screening effects for the Galactic halo and solar-reflected dark matter detection in semiconductor targets

Recently, the importance of the electronic many-body effect in the dark matter (DM) detection has been recognized, and a coherent formulation of the DM-electron scattering in terms of the dielectric response of the target material has been well established in literatures. In this paper, we put relevant formulas into practical density functional theory (DFT) estimation of the excitation event rates for the diamond and silicon semiconductor targets. Moreover, we compare the event rates calculated from the energy loss functions with and without the local field effects. For a consistency check of this numerical method, we also compare the differential spectrum and detection reach of the silicon target with those computed with the GPAW code. It turns out that these DFT approaches are quite consistent and robust. As an interesting extension, we also investigate the in-medium effect on the detection of the solar-reflected DM flux in silicon-based detectors, where the screening effect is found to be less remarkable than on detection of the Galactic DM, due to the high energies of the reflected DM particles.

Automated summary

This paper explores the electronic many-body effect in dark matter (DM) detection, specifically focusing on the dielectric response of the target material in DM-electron scattering. Practical density functional theory (DFT) is used to estimate excitation event rates for diamond and silicon semiconductor targets, with comparisons made between energy loss functions calculated with and without local field effects. The numerical methods prove to be consistent and robust, and the study also investigates the impact of in-medium effects on the detection of solar-reflected DM flux in silicon-based detectors.