Neutral-current effects in $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$ on a $\psi$-like resonance

We suggest that the reaction $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$ on a $\psi$-like resonance may provide a method for testing theories of the weak neutral current. The method is based on the observation that the $\tau$ decay products from this reaction will have a forward-backward asymmetry induced by the polarization sensitivity of the $\tau$ decays. We point out that, to the extent that the $\psi$-like resonance stands above background, this reaction provides not only an improved counting rate but also relief from the radiative asymmetries that trouble proposals to measure neutral-current asymmetries in $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$.