Z' INTERFERENCE EFFECTS FROM TRISTAN TO LEP2

We discuss the potential of present e(+)e(-) colliders to probe for he avy Z' boson via its interference effects, in a model-independent fram ework. The leptonic channel is unambiguous, and thus favourable over t he hadronic ones. The effects on the leptonic cross section sigma(mu m u) and the forward-backward difference sigma(FB), induced by a heavy Z ' with arbitrary couplings, are uniquely determined at LEP2 energies. It results in negative deviations from the standard model predictions, due to destructive gamma - Z' and Z - Z' interferences. This distinct ive property could be useful in discriminating Z' effects from other n ew physics signals. Comparison of the e(+)e(-) collider potentials ind icates that already after one year of operation, LEP2 will achieve a s ensitivity to Z' that exceeds the current one at TRISTAN. (C) 1997 Pub lished by Elsevier Science B.V.