  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.
