Puzzles of Dark Matter - More Light on Dark Atoms?

TL;DR

This paper explores a novel dark matter model involving O-helium atoms, which could explain DAMA's results through nuclear interactions, while remaining elusive to other detection methods.

Contribution

It introduces the O-helium atom model as a dark matter candidate and explains DAMA's signals via specific nuclear interactions, addressing discrepancies with other experiments.

Findings

O-helium atoms can produce annual modulation signals in NaI detectors.

The model predicts no signals in xenon or helium-based detectors.

It accounts for DAMA's results without conflicting with null results elsewhere.

Abstract

Positive results of dark matter searches in experiments DAMA/NaI and DAMA/LIBRA confronted with results of other groups can imply nontrivial particle physics solutions for cosmological dark matter. Stable particles with charge -2, bound with primordial helium in O-helium "atoms" (OHe), represent a specific nuclear-interacting form of dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground Dark matter detection using its nuclear recoil. However, low energy binding of OHe with sodium nuclei can lead to annual variations of energy release from OHe radiative capture in the interval of energy 2-4 keV in DAMA/NaI and DAMA/LIBRA experiments. At nuclear parameters, reproducing DAMA results, the energy release predicted for detectors with chemical content other than NaI differ in the most cases from the one in DAMA detector. Moreover there is no bound systems of OHe with light and heavy nuclei, so that there is no radiative capture of OHe in detectors with xenon or helium content. Due to dipole Coulomb barrier, transitions to more energetic levels of Na+OHe system with much higher energy release are suppressed in the correspondence with the results of DAMA experiments. The proposed explanation inevitably leads to prediction of abundance of anomalous Na, corresponding to the signal, observed by DAMA.