Mirror families in electro-weak symmetry breaking

We study symmetry breaking in a left-right symmetric extension of the Standard Model with mirror fermions, one for each Standard-Model fermion. The new particles assist a top-quark condensate in breaking electro-weak symmetry. Half of the fermions acquire electro-weak-invariant masses at around 500 GeV and would be probably accessible at future high-energy experiments like LHC or NLC. The contributions to the S and T parameters are small and negative in accordance with electro-weak precision data.