Indirect detection of low mass dark matter in direct detection experiments with inelastic scattering

We revisit the detection of luminous dark matter in direct experiments. In this scenario, scatters endothermically to produce an excited state, which decays a photon. explore ways electron recoil signal from decay photon can be differentiated other potential signals with narrow spectral shape. find that larger volume/exposure xenon detectors will unable differentiate origin without significant improvements detector energy resolution around order magnitude. also what learned about generic higher detector. Motivated by advancements solid-state detectors, we sub-eV enables discovery LDM presence background levels would otherwise make observation impossible. used determine shape spectrum and thus constrain mass velocity distribution.