  In theories of Partial Compositeness the top quark is a mixture of a
composite and an elementary state, and as a consequence its interactions with
gauge bosons are expected to deviate from those of a point-like object. At
sufficiently large energies, such deviations cannot be parametrized by the
leading effective field theory operators and form factors (i.e. energy
dependent interactions) must be introduced. In this work, we argue that such
effects might appear at relatively low energies with interesting
phenomenological consequences. In analogy to the proton electromagnetic
interactions, we devise a simplified phenomenological model that parametrizes
the top-quark interactions with gluons in terms of two form factors. We study
the implications of these interactions in top-quark and heavy top-partner pair
production at a hadron collider.
