Perturbative unitarity constraints on general image models and collider implications Original Research Article

We study perturbative unitarity constraints on general image models by considering the high-energy behavior of fermion scattering into gauge bosons. In most cases we survey, a image boson with a comparable mass must be present for the theory to be consistent, with fixed couplings to the standard model gauge bosons and fermions. Applying these results to a class of image models which explains the top quark forward–backward asymmetry observed at the Tevatron, we find that a image must exist with a mass below 7–8 TeV and sizable coupling to the light quarks. While such a image is strongly constrained by existing experiments, we show that the LHC can explore the entire mass range up to the unitarity limit. We also show how it is possible, by raising the image mass consistent with unitarity, to explain the CDF Wjj excess in terms of a light image, without generating an excess in Zjj events.