Quantum mechanical numerical model of interaction of dark atom with the nucleus

The hypothesis of composite X-helium (XHe) dark atoms  electrically neutral atom-like bound states formed by stable doubly negatively charged particles X and primordial helium nuclei — offers a particular approach to solving the problems of direct searches for dark matter particles. The talk will present a developed self-consistent quantum-mechanical numerical model of the interaction of a dark atom with a nucleus of ordinary matter, considering nuclear, Coulomb, centrifugal, and Stark interaction potentials. The obtained results for the interaction of XHe with sodium and iodine nuclei show a key selectivity: while the total effective potential for the sodium nucleus supports its radiative capture by the dark atom into a single low-energy bound state with binding energy in the range 1–6 keV, and the radiative capture cross section yields a count rate consistent with the amplitude of the annual modulation signal in the DAMA/LIBRA experiment, the corresponding radiative capture rates of the iodine nucleus by the dark atom are suppressed. The resulting selectivity of signal generation in a detector depending on its nuclear composition naturally explains the observed signal in NaI detectors and its absence in experiments with heavier target nuclei.