Constraints on light dark matter from primordial black hole evaporation at dark matter direct detection experiments

TL;DR

This work investigates light dark matter produced by PBH Hawking evaporation and its detectability in underground direct-detection experiments. It develops a framework to compute galactic and extragalactic PBHBDM fluxes, includes attenuation in the Earth, and translates fluxes into predictions for electron- and nucleus-recoils in XENONnT, PandaX-4T, and LZ. Using the latest data, the authors derive 2σ constraints on DM–electron and DM–nucleus cross sections and place limits on the present-day PBH dark matter fraction $f_{ m PBH}$, as well as the initial abundance parameter $\beta'_{ m PBH}$ for fully evaporated PBHs. The results show that PBHBDM can yield competitive constraints for sub-GeV DM, highlighting the complementarity between direct-detection bounds and cosmological observations, and they incorporate PBH mass evolution to extend constraints into the fully evaporated regime.

Abstract

Primordial black holes (PBHs) are able to produce light dark matter (DM) particles via Hawking radiation, and yield a flux of boosted DM that can be probed at underground DM direct detection experiments. We analyze both galactic and extragalactic contributions to the differential flux of light DM from PBH evaporation, and then compute the expected event rate from PBH boosted DM scattering off electrons or nuclei after taking into account the attenuation effect. Using recent data from DM direct detection experiments XENONnT, PandaX-4T and LZ, we set constraints on both DM-electron and DM-nucleus scattering cross sections, as well as the fraction of DM composed of PBHs $f_{\rm PBH}$ for $9\times10^{14}-1\times10^{16}\,\mathrm{g}$ PBHs that are not fully evaporated today. We also investigate the spectral evolution induced by Hawking evaporation throughout the evaporation and post-evaporation regimes. The constraints on the PBH mass are then extended into the $1\times10^{13}-6\times10^{14}\,\mathrm{g}$ window for fully evaporated PBHs.

Figures (8)

• Figure 1: Differential DM flux at Earth as a function of the kinetic energy $T_\chi$ for $M_{\rm PBH}=10^{15}\,\mathrm{g}$ (red) or $10^{16}\,\mathrm{g}$ (blue), $m_\chi=1\,\mathrm{MeV}$ and $f_{\rm PBH}=1$. The dashed and dotted lines denote the galactic and extragalactic components, respectively, while solid lines show their sum.
• Figure 2: The PBHBDM flux distribution at the detector as a function of DM kinetic energy with $M_{\rm PBH}=10^{15}$ g, $f_{\rm PBH}=1.6\times 10^{-8}$ and the depth of detector $d=1$ km. We consider DM--electron scattering in Earth matter with ${\sigma_{\chi e}=10^{-28}\,\mathrm{cm^2}}$ (dashed) and ${\sigma_{\chi e}=10^{-34}\,\mathrm{cm^2}}$ (solid). The PBHBDM mass is taken as $m_{\chi}=0.1\,\mathrm{MeV}$ (red), $m_{\chi}=0.5\,\mathrm{MeV}$ (black) or $m_{\chi}=1.0\,\mathrm{MeV}$ (blue). The unattenuated flux reaching the detector is given by dotted line.
• Figure 3: $1/T_{e}^{\max}$ as a function of the DM mass $m_{\chi}$ at the detector with benchmark kinetic energies $T_{\chi}^{d} = 1\,\mathrm{MeV}$ (dash–dotted), $10^{-1}\,\mathrm{MeV}$ (solid), $10^{-3}\,\mathrm{MeV}$ (dashed), and $10^{-4}\,\mathrm{MeV}$ (dotted). The red solid vertical line indicates the mass of target particle $m_e$.
• Figure 4: The predicted event spectrum of DM-electron scattering (left) and DM--nucleus scattering (right) for XENONnT (top), PandaX (middle), and LZ (bottom) experiments. Black points denote the measured data with error bars, and the red solid curve is the background-only spectrum provided by each experiment. The blue dashed curve shows the total expectation event spectrum including the DM signal induced by PBHs also. The benchmark parameters are $M_{\rm PBH}=10^{15}\,\mathrm{g}$, $f_{\rm PBH}=1.6\times10^{-8}$, $m_\chi=1\,\mathrm{MeV}$, $\sigma_{\chi e}=10^{-32.5}\,\mathrm{cm}^2$ and $\sigma_{\chi n}^{\rm SI}=10^{-37}\,\mathrm{cm^2}$.
• Figure 5: Left: $2\sigma$ bounds on $\sigma_{\chi e}$ as a function of $m_{\chi}$. Other constraints from DarkSide-50 DarkSide:2022knj (orange), EDELWEISS2020 EDELWEISS:2020fxc (green), DAMIC-M DAMIC-M:2023gxo (indigo), SENSEI2025 SENSEI:2023zdf (purple), SuperCDMS2025 SuperCDMS:2024yiv (pink), and XENONnT XENON:2024znc (brown) are shown for comparison. We also show the $90\%$ CL exclusion regions from CDEX-10 CDEX:2024xqm (cyan) for PBHBDM with the same $f_{\rm PBH}$ and $M_{\rm PBH}$ parameters. Right: $2\sigma$ bounds on $\sigma_{\chi n}^{\mathrm{SI}}$ as a function of $m_{\chi}$. The gray region shows the constraint from CRESST CRESST:2022lqw (gray). Both panels assume $M_{\mathrm{PBH}}=10^{15}\,\mathrm{g}$ and $f_{\mathrm{PBH}}=1.6\times10^{-8}$. The bounds are from XENONnT (black line), PandaX (red line) and LZ (blue line).