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Excitonic contributions to dark matter-electron scattering

Nora Taufertshöfer1,*, Vanessa Zema2,3, Riccardo Catena4, Valerio Olevano5, and Nicola A. Spaldin1

  • *Contact author: nora.taufertshoefer@mat.ethz.ch
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Phys. Rev. Research 8, 013056 – Published 20 January, 2026

DOI: https://doi.org/10.1103/9b1j-fcvw

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 DM 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.

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Phys. Rev. Research 8, 013056– Published 20 January, 2026
  • Received 5 August 2025
  • Accepted 10 December 2025
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