Signals of universality violation in e+e- collisions

We examine distributions of leptons produced in e+e- collisions, by a family nonuniversal extra gauge boson Z′, suggested by the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}${\text{Sp}}(6)_{\text{L}}\otimes{\text{U}}(1)_Y$\end{document} model, and by other neutral gauge bosons occurring in left–right symmetric models and in superstring-inspired E6 models. We discuss how to distinguish the models by examining the couplings to fermions of the extra Z-boson through its leptonic production cross sections and asymmetries. We show how the universality violation inherent in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}${\text{Sp}}(6)_{\text{L}}\otimes{\text{U}}(1)_Y$\end{document} model enhances the discovery potential of Z′ at future planned and proposed e+e- colliders.