  Instead of the energy recoil signal at direct detection experiments, dark
matter appears always as missing energy at high energy colliders. For a
fermionc dark matter coupled with quarks and neutrino via absorption operators,
its production is always accompanied by an invisible neutrino. We study in
details the mono-X (photon, jet, and $Z$) productions at the Large Hadron
Collider (LHC). To make easy comparison between the collider and DM direct
detection experiments, we start from the quark-level absorption operators for
the first time. In other words, we study the model-independent constraints on a
generic fermionic absorption dark fermion. In addition, the interplay and
comparison with the possible detection at the neutrino experiment especially
Borexino is also briefly discussed. We find that for both spin-dependent and
spin-independent absorption of the dark matter, the experiments with light
nuclear target can provide the strongest constraints.
