Top Quark Condensation 1.1 Preliminary

We review a class of dynamical models in which top condensation occurs at the weak scale, giving rise to the large top quark mass and other phenomena. This typically requires a color embedding, SU (3) c → SU (3) 1 × SU (3) 2 , ergo " Topcolor. " Topcolor suggests a novel route to technicolor models in which sequential quarks condense under the Topcolor interaction to break electroweak symmetries. The top quark has arrived with a mass of ∼ 175 GeV. This is remarkably large in comparison to all other known fundamental particles, and coin-cidently equals the natural scale of electroweak interactions, 1/ 2 √ 2G F. The top quark mass may be dynamically generated, analogous to a constituent quark mass in QCD. Then the relevant question becomes: " Are there new strong interactions that are revealing themselves through the large top mass? " If the answer is no, then the most sensible scenario for physics beyond the standard model is something like the minimal supersymmetric standard model (MSSM). In this case the top quark mass is given by the infra–red renormalization group fixed point [1], and many of the successful predictions of unification are tied to this fact [2]. By itself, this is remarkable, because the infra–red renormalization group fixed point is really a consequence of the approximate scale invariance of the unified theory over the range of