Searches for new neutral gauge Z′ bosons at the e+e? International Linear Collider and their identification

The potential of the electron-positron International Linear Collider for searches for and the separation of signals induced by new neutral gauge bosons predicted by various classes of models featuring an extended gauge sector is investigated. The analysis presented in this article was performed for processes of annihilation fermion-pair production and was based on the use of differential polarization observables, which ensure a higher sensitivity (in relation to integrated observables) of the processes being considered to Z′-boson parameters. Thresholds for discovering and identifying new neutral gauge bosons associated with models belonging to the E ₆ and LR, as well as the ALR and SSM, classes are determined. In particular, it is shown that polarization experiments at a 0.5-TeV electron-positron collider of integrated luminosity 100 fb⁻¹ would make it possible to identify unambiguously the entire set of Z′-boson models (Z′_SSM, Z′ _φ , Z′ _η , Z′ _χ , Z′_LRS, and Z′_ALR) for M _Z′ < 6√s and to improve considerably the respective estimates expected from experiments with unpolarized particles.