Vector-like strong coupling theory with small S and T parameters

We propose a mechanism which reduces the size of the Peskin and Takeuchi's S and T parameters in models of dynamical electroweak symmetry breaking. It is interesting that not only S but also T parameters can be small even if there exists large isospin violation in fermion condensation. The point is that because of decoupling theorem these parameters are suppressed by a large SU(2)L x U(1)Y invariant mass which vector-like fermions can have. (author)