Test of $CP$ Violating Neutral Gauge Boson Vertices in $ e^+ e^-   \rightarrow \gamma Z $
  Forward-backward asymmetry in the process $e^+ e^- \rightarrow \gamma Z$ is proposed as a test for $CP$--violating anomalous $\gamma \gamma Z$ and $ \gamma Z Z$ couplings. Longitudinally polarized electron beams may be used to disentangle the effects of these couplings. We estimate possible limits that can be obtained from $e^+ e^-$ colliders at centre-of-mass energies of 200 GeV and 500 GeV. 
Debajyoti Choudhury and Saurabh D. Rindani