CP violating Z t anti-t and gamma t anti-t Couplings at a Future e+ e-   Collider
  The effect of new operators that give rise to CP-violating couplings of the type $Z t \bar{t}$ and $\gamma t \bar{t}$ are examined at future electron positron Linear Colliders (FLC). The impact of these CP-violating interactions over Standard Model predictions was studied for the process e+ e^- -> t anti-t with the subsequent decays t -> b l+ nu_l and anti-t -> anti-b l- anti-nu_l, called as dilepton mode, and t -> b l^+ nu_l and anti-t -> anti-b anti-q q' or t -> b q anti-q' and anti-t -> anti-b l- anti-nu_l, called as single lepton mode, where the final leptons are l = e or mu, and the final quarks are q(q')= u(d) or c(s). Polarized electron beam and CP observables and asymmetries are used to impose bounds on the anomalous couplings. 
S. M. Lietti and Hitoshi Murayama