A Unified Dark Matter Model in sUED

TL;DR

The paper introduces a SM singlet-extended sUED model where the DM candidate χ_- arises as the first KK mode of a right-handed neutrino. A light scalar s_0 enables Sommerfeld enhancement, explaining PAMELA, while s_0–electron couplings address DAMA via DM–electron scattering; the same framework yields a 1–1.6 TeV DM mass to fit ATIC/PPB-BETS and a correct relic abundance with y_M ∼ 1.2–1.6. To satisfy diffuse gamma-ray constraints, χ_- and the nearby KK mode s_1 must be highly degenerate (MeV-scale), and the model’s predicted collider and neutrino signals provide avenues for experimental tests. Overall, the sUED construction offers a unified explanation for multiple dark-matter signals with distinctive collider and astrophysical implications.

Abstract

We propose a dark matter model with standard model singlet extension of the universal extra dimension model (sUED) to explain the recent observations of ATIC, PPB-BETS, PAMELA and DAMA. Other than the standard model fields propagating in the bulk of a 5-dimensional space, one fermion field and one scalar field are introduced and both are standard model singlets. The zero mode of the new fermion is identified as the right-handed neutrino, while its first KK mode is the lightest KK-odd particle and the dark matter candidate. The cosmic ray spectra from ATIC and PPB-BETS determine the dark matter particle mass and hence the fifth dimension compactification scale to be 1.0-1.6 TeV. The zero mode of the singlet scalar field with a mass below 1 GeV provides an attractive force between dark matter particles, which allows a Sommerfeld enhancement to boost the annihilation cross section in the Galactic halo to explain the PAMELA data. The DAMA annual modulation results are explained by coupling the same scalar field to the electron via a higher-dimensional operator. We analyze the model parameter space that can satisfy the dark matter relic abundance and accommodate all the dark matter detection experiments. We also consider constraints from the diffuse extragalactic gamma-ray background, which can be satisfied if the dark matter particle and the first KK-mode of the scalar field have highly degenerate masses.

Figures (5)

• Figure 1: Feynman diagram of the main annihilation channel of $\chi_{-}$ in our model.
• Figure 2: The energy density distribution as a function of the positron energy $E$ (in GeV) for 1 TeV dark matter mass. The errors on this plot come from uncertainties of numerical simulations.
• Figure 3: Feynman diagram of the DM-electron elastic scattering.
• Figure 4: The allowed region (shaded) for $\mu$ vs $y_e$.
• Figure 5: Feynman diagram of the elastic scattering of $\chi_{-}$ with $\nu_{L}$.