Resonant Dark Matter

TL;DR

This work proposes resonant dark matter (rDM) as a mechanism to address the DAMA modulation while remaining compatible with null results from other detectors. rDM posits a velocity-dependent DM-nucleus cross section with a bound-state resonance producing a Breit-Wigner-like dependence on velocity, selecting a narrow window around the resonance speed $v_r$ with width $\delta$. A simple model embeds DM as the neutral component of a weak $SU(2)_W$ triplet with a charged partner mass splitting $\Delta \sim 10\ \mathrm{MeV}$, enabling an electromagnetic bound-state resonance with nuclei and potentially iodine-rich targets, which explains the DAMA/KIMS hints but suppresses signals in other experiments. The analysis demonstrates that rDM can fit DAMA's modulated spectrum while respecting unmodulated DAMA and KIMS bounds and outlines distinctive predictions, including enhanced modulation, element dependence, and possible gamma or neutron signals that arise from the resonance decay channels.

Abstract

It is usually assumed that dark matter direct detection is sensitive to a large fraction of the dark matter (DM) velocity distribution. We propose an alternative form of dark matter-nucleus scattering which only probes a narrow range of DM velocities due to the existence of a resonance, a DM-nucleus bound state, in the scattering - resonant dark matter (rDM). The scattering cross section becomes highly element dependent, has increased modulation and as a result can explain the DAMA/LIBRA results whilst not being in conflict with other direct detection experiments. We describe a simple model that realizes the dynamics of rDM, where the DM is the neutral component of a fermionic weak triplet whose charged partners differ in mass by approximately 10 MeV.