Excitonic contributions to dark matter-electron scattering
Abstract
We determine whether excitonic effects affect predictions of dark matter (DM)-electron scattering rates by calculating the energy- and momentum-dependent energy-loss function, including electron-hole interaction excitonic effects, for the dark-matter scintillating detector materials GaAs and NaI. By comparing our results using the Bethe-Salpeter equation in the framework of many-body perturbation theory, which explicitly includes excitonic effects, with those using the quasiparticle random-phase approximation, which includes only electron-electron interaction and crystal local-field effects, we find that excitonic effects in NaI significantly increase the predicted scattering rate at low energy and as a result improve the cross-section sensitivity considering a realistic background. In contrast, the predicted scattering rate and the DM-electron scattering cross-section for GaAs are minimally affected by excitonic effects.
Cite
@article{arxiv.2507.14345,
title = {Excitonic contributions to dark matter-electron scattering},
author = {Nora Taufertshöfer and Vanessa Zema and Riccardo Catena and Valerio Olevano and Nicola A. Spaldin},
journal= {arXiv preprint arXiv:2507.14345},
year = {2026}
}
Comments
7 pages, 4 figures, 5 pages supplemental material with 6 additional figures