CP-Violation in the Production of Tau-Leptons at TESLA with Beam   Polarization
  We study the prospects of discovering CP-violation in the production of tau-leptons in the reaction {e+e- --> tau+tau- at TESLA, an e+e- linear collider with center-of-mass energies of 500 or even 800 GeV. Non-vanishing expectation values of certain correlations between the momenta of the decay products of the two tau leptons would signalthe presence of CP-violation beyond the standard model. We study how longitudinal beam polarization of the electron and positron beams will enhance these correlations. We find that T-odd and T-even vector correlations are well suited for the measurements of the real and imaginary parts of the electric dipole form factors. We expect measurements of the real part with a precision of roughly 10^-20 ecm and of the imaginary part of 10^-17 ecm. This compares well with the size of the expected effects in many extensions of the standard model. 
B. Ananthanarayan, Saurabh D. Rindani, Achim Stahl