DAMA/LIBRA annual modulation and axion quark nugget dark matter model
The DAMA/LIBRA (DL) experiment shows 9.5σ evidence for an annual modulation in the (1–6) keV energy range, strongly suggesting that the observed modulation has a dark matter origin. However, the conventional interpretation in terms of weakly interacting massive particle–nucleon interaction is excluded by other experiments. We propose an alternative source of modulation in the form of neutrons, which have been liberated from surrounding material. Our computations are based on the so-called axion quark nugget (AQN) dark matter model, which was originally invented long ago to explain the similarity between the dark and visible cosmological matter densities, i.e., Ωdark∼Ωvisible. In our proposal, the annual modulation is shown to be generated in the keV energy range, which is consistent with the DL observation in (1–6) keV range. This keV energy scale in our proposal is mostly determined by spectral properties of the neutrinos emitted by the AQN dark matter particles, while the absence of the modulation with energies above 6 keV is explained by a sharp cutoff in the neutrino’s energy spectrum at ∼15  MeV. This proposal can be directly tested by COSINE-100, ANAIS-112, CYGNO, and other similar experiments. It can be also tested by studying the correlations between the signals from these experiments and the signatures from drastically different detectors designed for studies of infrasonic or seismic events using such instruments as distributed acoustic sensing.