Search for boosted keV-MeV light dark matter particles from evaporating primordial black holes at the CDEX-10 experiment

Abstract

We present novel constraints on boosted light dark matter particles (denoted as ``$\ensuremath{\chi}$'') from evaporating primordial black holes (PBHs) using $205.4\text{ }\text{ }\mathrm{kg}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{day}$ data from the China Jinping Underground Laboratory's CDEX-10 p-type point contact germanium detector with a 160 eVee analysis threshold. $\ensuremath{\chi}$ from PBHs with masses ranging from $1\ifmmode\times\else\texttimes\fi{}{10}^{15}\text{ }\text{ }\mathrm{g}$ to $7\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{ }\text{ }\mathrm{g}$ are searched in this work. In the presence of PBH abundance compatible with present bounds, our result excludes the $\ensuremath{\chi}$-nucleon elastic-scattering cross section region from $3.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}\text{ }\text{ }{\mathrm{cm}}^{2}$ to $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}29}\text{ }\text{ }{\mathrm{cm}}^{2}$ for $\ensuremath{\chi}$ of 1 keV to 24 MeV from PBHs with masses of $5\ifmmode\times\else\texttimes\fi{}{10}^{15}\text{ }\text{ }\mathrm{g}$, as well as from $1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}28}\text{ }\text{ }{\mathrm{cm}}^{2}$ to $7.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}28}\text{ }\text{ }{\mathrm{cm}}^{2}$ for $\ensuremath{\chi}$ of 1 keV to 0.6 MeV from PBHs with masses of $7\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{ }\text{ }\mathrm{g}$. If the $\ensuremath{\chi}$-nucleon elastic-scattering cross section can be determined in the future, the abundance of PBHs may be severely constrained by $\ensuremath{\chi}$ evaporation. With the lower threshold (160 eVee) of the CDEX-10 experiment compared to the previously used experiments, this work allows for a better reach at soft spectra produced by heavier PBHs, which demonstrates the vast potential of such a technical route to pursue $\ensuremath{\chi}$ from larger PBHs with a low threshold.