Detecting light dark matter with prompt-delayed events in neutrino experiments

We demonstrate the prompt-delayed signals induced by knockout neutrons from the quasi-elastic scattering in neutrino experiments provides a new avenue for detecting light dark matter. As an illustration, we consider the detection of atmospheric dark matter in the liquid scintillator detectors. The results show that the constraint on the DM-nucleon interaction from KamLAND is approximately one order of magnitude more stringent than those obtained from the elastic nuclear recoil signals in dark matter direct detection experiments. Furthermore, a larger volume neutrino experiment, such as JUNO, is expected to significantly enhance the light dark matter detection sensitivity through the quasi-elastic scattering.