Superweakly Interacting Massive Particles

TL;DR

This work considers the concrete examples of gravitino and graviton cold dark matter in models with supersymmetry and universal extra dimensions, respectively, and shows that super-WIMP dark matter satisfies stringent constraints from big bang nucleosynthesis and the cosmic microwave background.

Abstract

We investigate a new class of dark matter: superweakly-interacting massive particles (superWIMPs). As with conventional WIMPs, superWIMPs appear in well-motivated particle theories with naturally the correct relic density. In contrast to WIMPs, however, superWIMPs are impossible to detect in all conventional dark matter searches. We consider the concrete examples of gravitino and graviton cold dark matter in models with supersymmetry and universal extra dimensions, respectively, and show that superWIMP dark matter satisfies stringent constraints from Big Bang nucleosynthesis and the cosmic microwave background.

Figures (4)

• Figure 1: Lifetimes for $\tilde{B} \to \tilde{G} \gamma$ (left) and $B^1 \to G^1 \gamma$ (right) for $\Delta m \equiv m_{\text{WIMP}} - m_{\text{SWIMP}}$ and $m_{\text{SWIMP}} = 0.1~\text{TeV}$ (long dashed), $0.3~\text{TeV}$ (short dashed), and $1~\text{TeV}$ (solid).
• Figure 2: The photon energy release $\varepsilon_\gamma Y_{\text{SWIMP}}$ for various $m_{\text{SWIMP}}$ in TeV in the gravitino (left) and graviton (right) superWIMP scenarios. We fix $\Omega_{\text{SWIMP}} = 0.23$; $\varepsilon_\gamma Y_{\text{SWIMP}}$ scales linearly with $\Omega_{\text{SWIMP}}$. BBN constraints exclude the shaded regions Cyburt:2002uv; consistency of the CMB with a black-body spectrum excludes regions above the CMB contours.
• Figure 3: Diffuse photon fluxes (solid) for $m_{\text{SWIMP}} = 1~\text{TeV}$, $\Omega_{\text{SWIMP}} = 0.23$, and $\Delta m = 1~\text{GeV}$ (solid) and $10~\text{GeV}$ (long dashed), and upper bounds from observations (short dashed).
• Figure 4: Regions of the $(m_{\text{SWIMP}}, \Delta m)$ plane excluded by BBN, CMB, and diffuse photon constraints. The shaded regions and the regions below the CMB contours are excluded.