The measurement of the nonelectromagnetic forward-backward charge asymmetry in the reaction $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ at $\sqrt{s}\sim 34.6$ GeV and in the angular region $0<\left|cos\theta \right|<\mathrm{}0.8\mathrm{}$ is reported. With a systematic error less than 1%, we observe an asymmetry of (-8.1±2.1)%. This is in agreement with the standard electroweak theory prediction of (-7.6±0.6)%. The weak-current coupling constants are also reported.

• Received 30 April 1982

DOI:https://doi.org/10.1103/PhysRevLett.48.1701