Top quark associated production of the neutral top-pion at high energy $e^{+}{e}^{-}$ colliders

In the context of topcolor-assisted technicolor (TC2) models, we calculate the associated production of the neutral top-pion ${\pi }_t^0$ with a pair of top quarks via the process $e^{+}{e}^{-}⟶t\bar{t}{\pi }_t^0$. We find that the production cross section is larger than that of the process $e^{+}{e}^{-}⟶t\bar{t}H$ both in the standard model (SM) and in the minimal supersymmetric SM. With reasonable values of the parameters in TC2 models, the cross section can reach $20fb$. The neutral top-pion ${\pi }_t^0$ may be direct observed via this process.