Low-energy structure of little Higgs models

Abstract

The mechanism of electroweak symmetry breaking in little Higgs models is analyzed in an effective field theory approach. This enables us to identify observable effects irrespective of the specific structure and content of the heavy degrees of freedom. We parametrize these effects in a common operator basis and present the complete set of anomalous contributions to gauge boson, Higgs boson, and fermion couplings. If the hypercharge assignments of the model retain their standard form, electroweak precision data are affected only via the S and T parameters and by contact interactions. As a proof of principle, we apply this formalism to the minimal model and consider the current constraints on the parameter space. Finally, we show how the interplay of measurements at the CERN LHC and a linear collider could reveal the structure of these models.