Probing topcolor-assisted technicolor models from like-sign tau pair production in e gamma collisions

We consider the contributions of the extra gauge boson Z' to the like sign $\tau$ production process $e^-\gamma\to e^+(\mu^+)\tau^-\tau^-$, induced by the tree-level flavor changing interactions. Since these rare production are far below the observable level in the Standard Model and other popular new physics models such as the minimal supersymmetric model, we find that Z' can give significant contributions to this process, and with reasonable values of the parameters in TC2 models, the cross section can reach several tens of fb and may be detected at the $e\gamma$ collisions.