Direct Detection Constraints on Dark Photons with CDEX-10 Experiment at the China Jinping Underground Laboratory

Abstract

We report constraints on the dark photon effective kinetic mixing parameter ($\hat{I}º$) with data taken from two $p$-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90\% confidence level upper limits on $\hat{I}º$ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses ($m_V$) from 10 to 300 eV/$c^2$ in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90\% confidence level with $m_V$ from 0.1 to 4.0 keV/$c^2$ are set from 449.6 kg-day data, with a minimum of $\hat{\mathrm{I}}º=1.3\times 10^{-15}$ at ${\mathrm{m}}_{\mathrm{V}}=200eV/{\mathrm{c}}^2$.

5 pages, 6 figures