DYNAMICAL ELECTROWEAK SYMMETRY BREAKING： IMPLICATIONS OF THE H^0

1. Introduction and Phenomenology In theories of dynamical electroweak symmetry breaking, the electroweak interactions are broken to electromagnetism by the vacuum expectation value of a composite operator, typically a fermion bilinear. In these theories, the longitudinal compo- nents of the massive weak bosons are identified with composite Nambu-Goldstone bosons arising from dynamical symmetry breaking in a strongly-coupled extension of the standard model. Viable theories of dynamical electroweak symmetry breaking must also explain （or at least accommodate） the presence of an additional composite scalar state to be identified with the H^0 scalar boson [1,2] - a state unlike any other observed to date.