Y. Wang, Q. Yue, S. K. Liu et al.
Improved limits on solar axions and bosonic dark matter from the CDEX-1B experiment using the profile likelihood ratio method
Phys. Rev. D 101, 052003 (2020)
We present the improved constraints on couplings of solar axions and more generic bosonic dark matter particles using 737.1 kg days of data from the CDEX-1B experiment. The CDEX-1B experiment, located at the China Jinping Underground Laboratory, primarily aims at the direct detection of weakly interacting massive particles using a p-type point-contact germanium detector. We adopt the profile likelihood ratio method for analysis of data in the presence of backgrounds. An energy threshold of 160 eV was achieved, much better than the 475 eVof CDEX-1A with an exposure of 335.6 kg days. This significantly improves the sensitivity for the bosonic dark matter below 0.8 keV among germanium detectors. Limits are also placed on the coupling g_Ae < 2.48 × 10⁻¹¹ from Compton, bremsstrahlung, atomic-recombination, and deexcitation channels and g^eff _AN × g_Ae < 4.14 × 10⁻¹⁷ from a ⁵⁷Fe M1 transition at 90% confidence level.