On the dynamical symmetry breaking of the electroweak interactions by the top quark

We discuss the electroweak gauge symmetry breaking triggered by a new strong attractive interaction to condensate fermion-antifermion, and topcolor is a prototype. To deal with the fermion pairing, a general method based on the Hubbard–Stratonovich transformation in the functional integral approach is used. We derive a formula which relates the W±, Z0 weak boson masses to that of the condensated fermion, thus generalizing the Pagels–Stokar formula obtained in QCD. The custodial SU(2) electroweak symmetry turns out to be systematically violated, the deviation of ρ≡MW2/(MZ2cos2θW) from unity is related to the new physics scale Λ. Some phenomenological consequences of the top-pair condensation models are discussed. Distinctive signatures of the tt scalar bound state, a Higgs boson like denoted by Ht, are the dominant decay modes Ht→ϒ+γ , Ht→ϒ+Z0, and Ht→B∗+B∗.