Phenomenology of an extra neutral gauge boson in electron-positron collisions

Models with an extra neutral gauge boson (2') are discussed. We review present limits on the properties of such a 2' which follow from requiring that the Z" mass not be shifted excessively through mixing, from neutral current experi- ments, and from the structure of the mass matrix which follows from the Higgs content of particular theories. We then examine what extensions in sensitivity can come from electron-positron annihilation experiments at the 2 peak, with emphasis on the importance of cross-section measurements for final states involv- ing lepton or quark pairs, followed by asymmetry measurements with polarized beams. Finally, we consider the additional information provided by asymmetry measurements in electron-positron collisions at energies above the 2.