Low-energy phenomenology of some supersymmetric E6-breaking patterns

We examine several patterns of breaking for supersymmetric and nonsupersymmetric E6 theories that lead to an extra U(1) symmetry which at low energies (TeV) can reveal itself by the existence of an extra Z boson. We examine the phenomenological implications of such theories, including the predictions for the proton lifetime, the electroweak mixing angle, and the couplings of all the fermions to the new Z boson. In addition, we examine the constraints on the mass and width of the second Z from the present neutral-current and CERN pp» collider data. This analysis is especially relevant in light of recent results from superstring theories.