The plot below shows the sensitivity of the 40 m MATHUSLA detector to hadronically decaying LLPs produced in exotic Higgs boson decays, assuming an integrated luminosity of 3 inverse ab.

The solid red curve shows the exclusion reach from a realistic background-free search for DVs with with 49% signal reconstruction efficiency after background vetoes are applied. For comparison, the dashed black curve shows idealized reach for 4 decays in the decay volume. We also show the current Br(h→invis) limit from ATLAS [https://arxiv.org/abs/2301.10731] (purple shading) and the HL-LHC projection [https://cds.cern.ch/record/2703572] (purple line); current ATLAS constraints from searches for 1 or 2 DVs (blue shading) and 2 DVs (green shading) in the muon system [https://arxiv.org/abs/1811.07370, https://arxiv.org/abs/2203.00587]; current CMS constraints from searches for 1 or 2 LLP decays in the muon system [https://arxiv.org/abs/2402.01898] (gray shading); projections for an ATLAS 1DV search in the muon system at the HL-LHC [https://arxiv.org/abs/1605.02742] (blue dashed); and the idealized sensitivity of CODEX-b [https://arxiv.org/abs/1911.00481] (orange dashed).