Singlet Fermionic Dark Matter explains DAMA signal

TL;DR

The paper investigates a Higgs-portal model with a light singlet fermionic dark matter candidate $\psi$ to explain the DAMA annual modulation while matching the WMAP relic density. The mechanism relies on a light singlet-like Higgs $h_2$ with small mixing $|\sin\theta| \lesssim 0.02$ and $m_{h_2} \lesssim m_\psi$, where the dominant annihilation channel $\psi\bar{\psi} \to h_2 h_2$ boosts the annihilation cross-section to achieve $\Omega h^2 \sim 0.1$. A parameter scan identifies viable regions with $m_{h_1} \approx 120$ GeV, $m_{h_2} \approx 1$--$10$ GeV, and $m_\psi \approx 1$--$10$ GeV that yield spin-independent cross-sections $\sigma_p^{SI} \sim 10^{-4}$ pb in agreement with the DAMA region and without conflicting with other null results. The study demonstrates that a simple Higgs-portal framework can simultaneously satisfy collider and cosmological constraints, providing a testable explanation for DAMA through light DM phenomenology.

Abstract

It has been suggested that, considering channeling effect, the order of a few GeV dark matters which are elastically scattered from detector nuclei might be plausible candidates reconciling the DAMA annual modulation signal with the results of other null experiments. We show that Singlet Fermionic Dark Matter can be such a dark matter candidate, simultaneously providing the correct thermal relic density which is consistent with the WMAP data.

Figures (3)

• Figure 1: Dominant diagram for spin-independent DM-nucleon scattering, with a low mass of the singlet-like Higgs $h_2$.
• Figure 2: Dominant diagram for DM pair annihilation, when $m_{\psi} \lesssim m_{h_2}$.
• Figure 3: Spin-independent cross section for DM-nucleon scattering as a function of DM mass $m_{\psi}$. The red points are the predictions for the light singlet fermionic dark matter and the cyan regions are DAMA signal regions. Also denoted are the upper limits from various DM search experiments.