Constraints on gauged B-3L(tau) and related theories

Abstract

We consider extensions of the Standard Model with an extra U(1) gauge boson which couples to B − (αLe + βLµ + γLτ ) with α + β + γ = 3. We show that the extra gauge boson necessarily mixes with the Z, leading to potentially significant corrections to the Z f f vertex. The constraints on the size of this correction imposed by the Z–pole data from LEP and SLD are derived.