  In Higgs portal models of fermion dark matter, scalar couplings are
unavoidably suppressed by strong bounds from direct detection experiments. As a
consequence, thermal dark matter relics must coexist with mediators in a
compressed spectrum of dark particles. Small couplings and small mass
splittings lead to slow mediator decays, leaving signatures with displaced
vertices or disappearing tracks at colliders. We perform a comprehensive
analysis of long-lived mediators at the LHC in the context of a minimal dark
matter model with a naturally small Higgs portal, also known as the wino-bino
scenario in supersymmetry. Existing searches for disappearing charged tracks
and displaced hard leptons already exclude tiny portal couplings that cannot be
probed by current direct and indirect detection experiments. For larger portal
couplings, we predict new signatures with displaced soft leptons, which are
accessible with run-II data. Searches for displaced particles are sensitive to
weakly coupling mediators with masses up to the TeV scale, well beyond the
reach of prompt signals.
