A SUPERSTRING Z' AT O(1TEV)

We discuss the scale and effects of a new neutral gauge boson, Z', in our recently derived superstring standard-like model, which is a combination of B - L and T3R and provides a mechanism to suppress proton decay. We show that the mass and mixing angle of the Z' with the standard model Z depend only on M(Z) and M(W). For the central values of M(Z) and M(W) from recent experiments, M(Z) approximately 1000 GeV. We discuss the effect of Z-Z' mixing on the width of the Z and investigate the effect on primordial nucleosynthesis calculations, from which we find that the existence of light right-handed neutrinos with a Z' is excluded unless M(Z), greater-than-or-equal-to 1.5 TeV.