Signatures of a second heavy neutral vector boson in e+e- annihilation

Some grand unification models predict the existence of a second massive neutral vector boson which couples to fermions in much the same way as the well-known Z boson in the standard model of electroweak interactions. Among the possibilities, e+e- annihilations at high energies may provide a means of observing the effects of this particle. We analyze the process e+e-→ff-bar in the contest of a SU(2) x U(1) x U(1) theory with a view to study the anomalies in the angular distribution of the differential cross section. Two models are worked out as illustrations and low-energy predictions compared with current data from SLAC and DESY