Constraints on Spin-Independent Nucleus Scattering with sub-GeV Weakly Interacting Massive Particle Dark Matter from the CDEX-1B Experiment at the China Jin-Ping Laboratory

Abstract

We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses ($m_{\chi }$) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg$\cdot$day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg$\cdot$day exposure and 250 eVee threshold for AM analysis. The sensitive windows in $m_{\chi }$ are expanded by an order of magnitude to lower DM masses with Migdal effect incorporated. New limits on ${\sigma }_{\chi N}^{\mathrm{SI}}$ at 90\% confidence level are derived as $2\times$10${}^{-32}\sim 7\times$10${}^{-35}$ $\mathrm{c}{\mathrm{m}}^2$ for TI analysis at $m_{\chi }\sim$ 50$-$180 MeV/$c^2$, and $3\times$10${}^{-32}\sim 9\times$10${}^{-38}$ $\mathrm{c}{\mathrm{m}}^2$ for AM analysis at $m_{\chi }\sim$75 MeV/$c^2-$3.0 GeV/$c^2$.

Comments: 5 pages, 4 figures