QCD exotics versus a Standard Model Higgs
  The present collider data put severe constraints on any type of new strongly-interacting particle coupling to the Higgs boson. We analyze the phenomenological limits on exotic quarks belonging to non-triplet SU(3)_C representations and their implications on Higgs searches. The discovery of the Standard Model Higgs, in the experimentally allowed mass range, would exclude the presence of exotic quarks coupling to it. Thus, such QCD particles could only exist provided that their masses do not originate in the SM Higgs mechanism. 
Victor Ilisie and Antonio Pich
hep-ph hep-ex