Multi-Higgs Boson Probes of the Dark Sector

We consider dark sectors with spontaneously broken gauge symmetries, where cascade decays of the dark sector fields naturally produce multi-Higgs boson final states along with dark matter. Our study focuses on two and three Higgs boson final states with missing energy using a multivariate analysis with Boosted Decision Trees. We find that the di-Higgs boson channel is quite promising for the $\bar b b + \gamma \gamma$ and $\bar b b + \bar \ell \ell$ decay modes. The tri-Higgs boson final state with missing energy, on the other hand, appears to be beyond the reach of the LHC in analogous channels. This may change when fully hadronic Higgs boson decays are considered.