Top-charm associated production at high energy e+e− colliders in the standard model

The flavor changing neutral current tcV (V=γ,Z) couplings in the production vertex for the process e+e−→tc̄ or t̄c in the standard model are investigated. The precise calculations keeping all quark masses non-zero are carried out. The total production cross section is found to be 1.84×10−9 fb at s=200 GeV and 0.572×10−9 fb at s=500 GeV respectively. The result is much smaller than that given in Ref. by a factor of 10−5.