Detecting the neutral top-pion at $e^{+}e^{-}$ colliders
  We investigate some processes of the associated production of a neutral top-pion $\Pi^{0}_{t}$ with a pair of fermions($e^{+}e^{-}\to f\bar{f}\Pi^{0}_{t}$) in the context of top-color-assisted technicolor(TC2) theory at future $e^{+}e^{-}$ colliders.   The studies show that the largest cross sections of the processes $e^{+}e^{-}\to f'\bar{f'}\Pi^{0}_{t}(f'=u,d,c,s,\mu,\tau)$ could only reach the level of 0.01fb, we can hardly detect a neutral top-pion through these processes. For the processes $e^{+}e^{-}\to e^{+}e^{-}\Pi^{0}_{t}$, $e^{+}e^{-}\to t\bar{t}\Pi^{0}_{t}$ and $e^{+}e^{-}\to b\bar{b}\Pi^{0}_{t}$, the cross sections of these processes are at the level of a few fb for the favorable parameters and a few tens, even hundreds, of neutral top-pion events can be produced at future $e^{+}e^{-}$ colliders each year through these processes. With the clean background of the flavor-changing $t\bar{c}$ channel, the top-pion events can possibly be detected at the planned high luminosity $e^{+}e^{-}$ colliders. Therefore, such neutral top-pion production processes provide a useful way to detect a neutral top-pion and test the TC2 model directly. 
Xuelei Wang, Yueling Yang, and Bingzhong Li