Naturally resonant two-mediator model of self-interacting dark matter with decoupled relic abundance

Naturally resonant two-mediator model of self-interacting dark matter with decoupled relic abundance
Martin Drobczyk
arXiv:2506.22997v3 Announce Type: replace-cross
Abstract: We propose a minimal, fully thermal mechanism that resolves the long-standing tension between achieving the observed dark-matter relic abundance and explaining the astrophysical signatures of self-interactions. The framework introduces two mediators: a light scalar $phi$ (MeV scale) that yields the required, velocity-dependent self-interactions, and a heavy scalar resonance $Phi_h$ (TeV scale) with mass $m_{Phi_h}!approx!2m_chi$ that opens an $s$-channel resonant annihilation during freeze-out. This clearly decouples early-universe annihilation from late-time halo dynamics. A detailed numerical analysis identified a narrow predictive island of viability. A representative benchmark with $m_chi!=!600$~GeV, $m_phi!=!15$~MeV, and $m_{Phi_h}!simeq!1.2$~TeV reproduces the relic density and yields $sigma_T/m_chisim 0.1$–$1~mathrm{cm}^2!/mathrm{g}$ at dwarf-galaxy velocities while satisfying cluster bounds. The model makes sharp, testable predictions: a narrow $tbar t$ resonance near $1.2$~TeV within HL-LHC reach, and a spin-independent direct-detection signal $sigma_{rm SI}!sim!7times10^{-48},mathrm{cm}^2$ within next-generation sensitivity. As an optional UV completion, we show that walking $mathrm{SU}(3)_H$ gauge theory with $N_f=10$ naturally realizes the near-threshold relation $m_{Phi_h}!approx!2m_chi$ and can furnish an effective anomalous dimension $gamma!approx!0.5$ which underlies a density-responsive dark-energy sector, suggesting a unified origin for the dark sector.arXiv:2506.22997v3 Announce Type: replace-cross
Abstract: We propose a minimal, fully thermal mechanism that resolves the long-standing tension between achieving the observed dark-matter relic abundance and explaining the astrophysical signatures of self-interactions. The framework introduces two mediators: a light scalar $phi$ (MeV scale) that yields the required, velocity-dependent self-interactions, and a heavy scalar resonance $Phi_h$ (TeV scale) with mass $m_{Phi_h}!approx!2m_chi$ that opens an $s$-channel resonant annihilation during freeze-out. This clearly decouples early-universe annihilation from late-time halo dynamics. A detailed numerical analysis identified a narrow predictive island of viability. A representative benchmark with $m_chi!=!600$~GeV, $m_phi!=!15$~MeV, and $m_{Phi_h}!simeq!1.2$~TeV reproduces the relic density and yields $sigma_T/m_chisim 0.1$–$1~mathrm{cm}^2!/mathrm{g}$ at dwarf-galaxy velocities while satisfying cluster bounds. The model makes sharp, testable predictions: a narrow $tbar t$ resonance near $1.2$~TeV within HL-LHC reach, and a spin-independent direct-detection signal $sigma_{rm SI}!sim!7times10^{-48},mathrm{cm}^2$ within next-generation sensitivity. As an optional UV completion, we show that walking $mathrm{SU}(3)_H$ gauge theory with $N_f=10$ naturally realizes the near-threshold relation $m_{Phi_h}!approx!2m_chi$ and can furnish an effective anomalous dimension $gamma!approx!0.5$ which underlies a density-responsive dark-energy sector, suggesting a unified origin for the dark sector.