Present and Future sensitivity to a Z-prime

Abstract

Various extensions of the Standard Model, i.e. string inspired groups like E_6, extra dimensions, 'deconstruction', predict additional vector bosons. In most cases these bosons can mix with the SM Z and this translates into a very high sensitivity of precision measurements which can be performed at the Z resonance. This aspect will be illustrated using SLD/LEP data and the possible impact on the Higgs boson mass indirect determination. An extrapolation to the accuracies which could be reached at FLC will be discussed. With accuracies available at GigaZ it will become possible to elucidate the origin the Z' and the symmetry breaking mechanism responsible for the mixing. Two examples show the possible impact of FLC on the LHC program.