Top-quark couplings to TeV resonances at future lepton colliders

We study the processes WLWL → tt̄ and WLZL → tb̄ (t̄b) at future lepton colliders as probes of the couplings of the top quark to resonances at the TeV scale. We consider the cases in which the dominant low energy feature of a strongly interacting electroweak symmetry breaking sector is either a scalar or a vector resonance with mass near 1 TeV. We find that future lepton colliders with high energy and high luminosity have great potential to sensitively probe these physics scenarios. In particular, at a 1.5 TeV linear collider with an integrated luminosity of 200 fb, we expect about 120 events for either a scalar or a vector to decay to tt̄, tb. Their leading partial decay widths, which characterize the coupling strengths, can be statistically determined to about 10% level.