Multiple $Z' o tar t$ signals in a 4D composite Higgs model

We study the production of top-antitop pairs at the Large Hadron Collider as a test bed for discovering heavy Z′ bosons belonging to a composite Higgs model, as in this scenario, such new gauge interaction states are sizeably coupled to the third-generation quarks of the Standard Model. We study their possible appearance in cross sections, as well as (charge and spin) asymmetry distributions. Our calculations are performed in the minimal four-dimensional formulation of such a scenario, namely the four-dimensional composite Higgs model, which embeds five new Z′s. We pay particular attention to the case of nearly degenerate resonances, highlighting the conditions under which these are separable in the aforementioned observables. We also discuss the impact of the intrinsic width of the new resonances on the event rates and various distributions. We confirm that the 14 TeV stage of the LHC will enable one to detect two such states, assuming standard detector performance and machine luminosity. A mapping of the discovery potential of the LHC for these new gauge bosons is given. Finally, from the latter, several benchmarks are extracted which are amenable to experimental investigation. © 2013 American Physical Society.