Weak Dipole Moment ofτine+e−Collisions with Longitudinally Polarized Electrons

It is pointed out that certain $\mathrm{CP}$-odd momentum correlations in the production and subsequent decay of tau pairs in $e^{+}{e}^{-}$ collisions get enhanced when the $e^{-}$ is longitudinally polarized. Analytic expressions for these correlations are obtained for the single-pion decay mode of $\tau$ when ${\tau }^{+}{\tau }^{-}$ have a "weak" dipole form factor (WDFF) coupling to $Z$. For $e^{+}{e}^{-}$ collisions at the $Z$ peak, a sensitivity of about (1-5) × ${10}^{-17\mathrm{}}$ e cm for the $\tau$ WDFF can be reached using a single ${\tau }^{+}{\tau }^{-}$ decay channel, with ${10}^6$ $Z\text{'}\mathrm{s}$ likely to be available at the Stanford Linear Collider with $e^{-}$ polarization of 62%-75%.