  We report first results from the investigation on probing dynamical mechanism
of the electroweak symmetry breaking using top quark. We consider the case
where the top mass originates from a fermion-antifermion pair condensate, which
necessitates (i)strong interaction to cause condensation, and (ii)4-fermi
interaction to give top mass. From the observed top mass and the unitarity
constraint, we obtain, for the 4-fermi interaction (ii), lower bounds for its
strength and upper bounds for its intrinsic new mass scale as we vary the type
of the strong interaction (i). Bethe-Salpeter and Schwinger-Dyson equations are
solved numerically to study the dynamical symmetry breaking effect
semi-quantitatively.
