Search for scalar superpartners of the top quark

The phenomenology of top squarks is investigated in the framework of a large class of models based on spontaneously-broken local supersymmetry, in which the top quark often has a scalar superpartner lighter than msub(t). We find that two-body (one-loop) decays of top squarks lighter than top quarks dominate over four-body (three-level) decays. We also focus on the changes expected in the decay patterns of the top quark given a light scalar top, and argue that the observation of top quarks decaying according to standard-model expectations would serve to rule out many models with light scalar top and light gauginos. (orig.)