Hidden vector dark matter

TL;DR

The paper presents a viable dark matter scenario where stability is enforced by a custodial symmetry in a hidden non-abelian vector sector that couples to the Standard Model exclusively through a Higgs portal scalar. Relic density is achieved via hidden-sector annihilations and can be largely decoupled from direct-detection signals when the Higgs portal coupling is small, while large portal couplings yield rich collider and indirect-detection prospects. A broad parameter space accommodates correct relic abundance and existing experimental constraints, with distinct regimes where either the hidden sector alone sets the abundance or Higgs-portal dynamics play a significant role. The framework supports testable predictions at colliders, direct-detection experiments, and potentially indirect-detection signals, and remains stable against higher-dimensional operators up to dimension-6, limiting the scale of any UV completion.

Abstract

We show that dark matter could be made of massive gauge bosons whose stability doesn't require to impose by hand any discrete or global symmetry. Stability of gauge bosons can be guaranteed by the custodial symmetry associated to the gauge symmetry and particle content of the model. The particle content we consider to this end is based on a hidden sector made of a vector multiplet associated to a non-abelian gauge group and of a scalar multiplet charged under this gauge group. The hidden sector interacts with the Standard Model particles through the Higgs portal quartic scalar interaction in such a way that the gauge bosons behave as thermal WIMPS. This can lead easily to the observed dark matter relic density in agreement with the other various constraints, and can be tested experimentally in a large fraction of the parameter space. In this model the dark matter direct detection rate and the annihilation cross section can decouple if the Higgs portal interaction is weak.

Figures (4)

• Figure 1: Annihilation diagrams with no DM particle in the final state
• Figure 2: Annihilation diagrams with one DM particle in the final state
• Figure 3: $g_\phi$ vs $v_\phi$ and $m_A$ vs $m_\eta$ leading to $0.091 \lesssim \Omega h^2 \lesssim 0.129$, for $10^{-7} < \lambda_m < 10^{-3}$, $m_h=120$ GeV and various values of $\lambda_\phi$: $\lambda_\phi= 10^{-4}$ (red), $\lambda_\phi= 10^{-3}$ (orange), $\lambda_\phi= 10^{-2}$ (green) and $\lambda_\phi= 10^{-1}$ (blue) (from left to right and top to bottom respectively). One also recognizes the $m_A =g_\phi v_\phi/2 \sim m_h/2$ resonant case curve.
• Figure 4: For $10^{-3} < \lambda_m < 1$ and $114.4\,\hbox{GeV} < m_h < 180~\hbox{GeV}$, values of $g_\phi$ vs $v_\phi$, $m_A$ vs $m_\eta$ and $m_A$ vs $\sigma(AN \rightarrow A N)$ leading to $0.091 \lesssim \Omega h^2 \lesssim 0.129$. $\lambda_\phi$ has been varied between $10^{-5}$ and $1$. Dots with $m_\eta\simeq 2 \, m_A$ proceed through resonance of the $\eta$ exchange diagrams (to $W^+W^-$, $ZZ$, $f \bar{f}$ or $hh$). Similarly dots with $m_h\simeq2 \, m_A$ similarly are dominated by the Higgs exchange diagrams (to $W^+W^-$, $ZZ$, $f \bar{f}$ or $\eta \eta$). Dots with $m_\eta <114.4$ GeV are for suppressed values of $\sin \beta$ to agree with the LEP constraints on the $h \rightarrow f \bar{f}$ branching ratio.