CP-violation in the production of τ-leptons at TESLA with beam polarization

Abstract

We study the prospects of discovering CP-violation in the production of τ leptons in the reaction e⁺e⁻→τ⁺τ⁻ 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 τ leptons would signal the 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 e cm and of the imaginary part of 10⁻¹⁷ e cm. This compares well with the size of the expected effects in many extensions of the standard model.