Top-quark partial compositeness beyond the effective field theory paradigm

Abstract

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.

Electroweak top couplings, partial compositeness, and top partner searches

“…On top of the coupling modifications of the top-associated currents, amplitudes receive corrections from propagating top partners. Similarly, a composite top substructure can lead to additional anomalous magnetic moments [112,121,122] as observed in nuclear physics [123]. At the considered order in the chiral expansion in this work, such terms arise at loop level [124,125] and at tree level via the direct propagation of top partners.…”