2020/02/29 by Noah Kurinsky, Daniel Baxter, D. Baxter +2
Physics and Astronomy · #Astrophysics #Atomic and Subatomic Physics Research #Dark Matter and Cosmic Phenomena #Dark matter #Detector #Electron #Event (particle physics) #Nuclear physics #Optics #Optoelectronics #Particle Detector Development and Performance #Particle physics #Physics #Plasmon #Scattering #Semiconductor #astro-ph.CO #cond-mat.mtrl-sci #hep-ex #hep-ph #physics.ins-det
paper · pdf · doi:10.1103/physrevd.102.015017
published as Phys. Rev. D 102, 015017 (2020) · 20 pages, 7 figures. Submitted to PRD
arxiv created 2020/03/24 · openalex publication_date 2020/07/20 · arxiv updated 2020/07/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a novel unifying interpretation of excess event rates observed in several dark matter direct-detection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of \ensuremath∼10 Hz/kg. However, none of these persistent excesses has yet been reported as a dark matter signal because individually, each can be attributed to different well-motivated but unmodeled backgrounds, and taken together, they cannot be explained by dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process, consistent with exciting a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several single-electron threshold detectors. At least one of these scenarios also yields the correct relic density from thermal freeze-out. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.