Signals for the Electroweak Symmetry Breaking Associated with the Top Quark
The mechanism of the electroweak symmetry-breaking (EWSB) is studied in the context of the heavy top quark, whose large mass may provide a clue as to the mechanism which generates the mass of the $W^\pm$ and $Z$ bosons. As a result, it seems quite likely that the top quark may be special in the sense that it is involved in dynamics not experienced by the light fermions. Examples of this include models such as the top-condensate model in which a bound state of top quarks condenses, generating both the top mass and the gauge boson masses, and supersymmetric models in which the large top Yukawa coupling naturally explains the EWSB by radiatively driving the squared mass of a scalar particle (which is positive at a large energy scale) negative at low energies. Specific collider signatures of the third family result from such scenarios, and can be used to test the hypothesis that the top plays a role in the EWSB. In particular, single top production, as a measure of the top's weak interactions, provides an excellent probe of nonstandard top quark properties. The physics of single top production at hadron colliders is carefully studied, with a particular eye towards what can be learned from single top, including the signs of new physics that may show up in the single top rate.