Sensitivity of a future high energy e+e− collider to Z′ bosons

Abstract

We consider the capability of a future high energy e+e− collider to search for the Z′ bosons associated with a U(1)′ gauge extension of the standard model. Even for Z′ masses well above the center of mass energy of the collider, the rates of production of e+e−, μ+μ−, unflavored jets, and b-tagged jets can reveal the presence of virtual Z′ exchange. We consider collider configurations with center-of-mass energy 200, 300, and 500 GeV, and show how various classes of Z′ model-lines can be probed with 100 fb−1 of integrated luminosity. We find that for order one couplings, Z′ masses on the order of several TeV can be discovered, depending on the collider energy. Our results suggest that a 200 GeV collision energy is unlikely to discover any of the Z′ models we consider that would not have already been visible in late stages of LHC running. For e+e−, but could still help refine understanding of the couplings and distinguish between different models collision energies of 300 GeV, parameter space beyond the reach of the LHC becomes accessible.