An extension of the standard model of electro-weak interactions by an extra abelian gauge boson is given, in which the extra gauge boson and the hypercharge gauge boson both couple to an axionic scalar in a form that leads to a Stueckelberg mass term. The theory leads to a massive Zʹ whose couplings to fermions are uniquely determined and suppressed by small mixing angles. Such a Zʹ could have a low mass and appear in e+e− collisions as a sharp resonance. The branching ratios into f ̅ f species, and the forward-backward asymmetry are found to have distinctive features. The model also predicts a new unit of electric charge eʹ = Qʹe, where Qʹ is in general irrational, in the coupling of the photon with hidden matter that is neutral under SU(2)L × U(1)Y .