Strongly coupled quarks in the standard model

For sufficiently strong Yukawa couplings the standard model goes over to the linear σ model. We point out that the associated heavy quarks may behave like strongly interacting low-energy u and d quarks so one cannot argue that very-heavy-quark systems will provide an easy test of QCD. An upper-quark-mass bound of about 1.5 TeV is found. (This should also apply to techniquarks.) Experimental confirmation of the scheme might come from the observation of very tightly bound baryons made from three heavy quarks