A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg day data taken from a $p$-type point contact germanium detector of the CDEX-10 experiment at China’s Jinping underground laboratory. New low-mass dark matter searching channels, neutral current fermionic DM absorption ($\chi +A\to \nu +A$) and DM-nucleus $3\to 2$ scattering ($\chi +\chi +A\to \varphi +A$), have been analyzed with an energy threshold of 160 eVee. No significant signal was found; thus new limits on the DM-nucleon interaction cross section are set for both models at the sub-GeV DM mass region. A cross section limit for the fermionic DM absorption is set to be $2.5\times {10}^{-46}{\mathrm{cm}}^2$ (90% C.L.) at DM mass of $10\mathrm{MeV}/c^2$. For the DM-nucleus $3\to 2$ scattering scenario, limits are extended to DM mass of 5 and $14\mathrm{MeV}/c^2$ for the massless dark photon and bound DM final state, respectively.

• Received 4 September 2022
• Accepted 7 November 2022

DOI:https://doi.org/10.1103/PhysRevLett.129.221802

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Published by the American Physical Society