WIMPless Dark Matter in Anomaly-Mediated Supersymmetry Breaking with Hidden QED

TL;DR

This work demonstrates that a simple AMSB-based hidden sector, realized as supersymmetric QED with $N_F$ flavors, can produce WIMPless dark matter whose relic density matches observations across a wide mass range. The dark matter is multi-component, consisting of hidden leptons and sleptons that annihilate to a massless hidden photon bath, leading to potentially observable self-interactions and contributions to $\Delta N_{\rm eff}$. The model yields a relic density largely independent of the hidden gauge coupling when $|\mu| \sim m_{\tilde{\gamma}}$, and it makes concrete predictions for $\Delta N_{\rm eff}$ (typically $\sim 0.2$–$0.4$ for $\xi_\infty=1$) and for a broad DM mass range ($\sim 10$ GeV to $10$ TeV) constrained by perturbativity and halo-shape bounds. Future Planck measurements and astrophysical observations will test these predictions, while the need for a concrete hidden-sector $\mu$-term mechanism and possible connectors to the visible sector offer directions for further model-building and phenomenology.

Abstract

In anomaly-mediated supersymmetry breaking, superpartners in a hidden sector have masses that are proportional to couplings squared, and so naturally freeze out with the desired dark matter relic density for a large range of masses. We present an extremely simple realization of this possibility, with WIMPless dark matter arising from a hidden sector that is supersymmetric QED with N_F flavors. Dark matter is multi-component, composed of hidden leptons and sleptons with masses anywhere from 10 GeV to 10 TeV, and hidden photons provide the thermal bath. The dark matter self-interacts through hidden sector Coulomb scatterings that are potentially observable. In addition, the hidden photon contribution to the number of relativistic degrees of freedom is in the range ΔN_eff ~ 0 - 2, and, if the hidden and visible sectors were initially in thermal contact, the model predicts ΔN_eff ~ 0.2 - 0.4. Data already taken by Planck may provide evidence of such deviations.

Figures (5)

• Figure 1: Allowed region in the $(N_F, |\mu|/m_{\tilde{\gamma}})$ parameter space of WIMPless dark matter from hidden SQED with $N_F$ flavors and global SU($N_F$) flavor symmetry. The lower and upper shaded regions are excluded by the requirements that the vacuum be stable and photinos decay, respectively. In the allowed region, multi-component dark matter is composed of $N_F$ degenerate flavors of hidden leptons $e_i$ and $N_F$ degenerate flavors of sleptons $\tilde{e}_i$. Contours of constant $m_{\tilde{e}_i}/m_{e_i}$ are shown.
• Figure 2: Contours of constant $\sqrt{\xi_f} M_{3/2}$, as determined by requiring $\Omega_{\text{tot}} \simeq 0.23$ in the $(N_F, |\mu|/m_{\tilde{\gamma}})$ parameter space.
• Figure 3: Contours of constant $M_{3/2}$ in the $(N_F, |\mu|/m_{\tilde{\gamma}})$ plane, with fixed $\xi_{\infty} = 1$, $\Omega_{\text{tot}} \simeq 0.23$, and $g_*^{\text{v}}(T_f^{\text{v}}) = g_*^{\text{SM}}$. $\Delta N_{\text{eff}}$ is the effective number of extra neutrinos, as given by Eq. (\ref{['dneff']}). The shaded region labeled "Non-Perturbative" is forbidden by the considerations of self-interactions and perturbativity discussed in Sec. \ref{['sec:selfinteractions']}. For fixed $\xi_{\infty}$ and $\Omega_{\text{tot}}$, $M_{3/2} \propto g_*^{\text{v}}(T_f^{\text{v}})^{-1/6}$.
• Figure 4: Contours of constant $\Delta N_{\text{eff}}$, the effective number of extra neutrinos in the $(N_F, |\mu|/m_{\tilde{\gamma}})$ parameter space for $M_{3/2} = 70$ and 80 TeV, $\Omega_{\text{tot}} \simeq 0.23$, and $g_*^{\text{v}}(T_f^{\text{v}}) = g_*^{\text{SM}}$. For fixed $\Omega_{\text{tot}}$, $\Delta N_{\text{eff}} \propto M_{3/2}^{-8} \, g_*^{\text{v}}(T_f^{\text{v}})^{-4/3}$.
• Figure 5: Contours of constant $m_{\text{DM}}^{\text{min}}$, the minimal lepton mass that is consistent with self-interaction bounds from the observation of elliptical halos, for $M_{3/2} = 40, 80, 200$, and 500 TeV, and $\Omega_{\text{tot}} = 0.23$. In the shaded region marked "Non-Perturbative," $m_{\tilde{\gamma}} > M_{3/2}$, signaling a breakdown of perturbativity. Note that the values of $m_{\text{DM}}^{\text{min}}$ are in units of GeV for the $M_{3/2} = 500~\text{TeV}$ panel, and in TeV for the others, as indicated.