  The scenario of the compressed mass spectrum between heavy quark and dark
matter is a challenge for LHC searches. However, the elastic scattering cross
section between dark matter and nuclei in dark matter direct detection
experiments can be enhanced with nearly degenerate masses between heavy quarks
and dark matter. In this paper, we illustrate such scenario with a vector dark
matter, using the latest result from LUX 2016. The mass constraints on heavy
quarks can be more stringent than current limits from LHC, unless the coupling
strength is very small. However, the compress mass spectrum with allowed tiny
coupling strength makes the decay lifetime of heavy quarks longer than the time
scale of QCD hadronization.
