Top-charm associated production at hadron colliders in the standard   model with large extra dimensions
  The precise calculations are carried out on the flavor changing neutral current couplings in the process $pp \to gg \to t\bar{c}(\bar{t}c)$ at the large hadron collider(LHC) and very large hadron collider(VLHC) in both frameworks of the minimal standard model(MSM) and its extension with extra dimensions. We find that the effects from the large extra dimensions can enhance the total cross section up to about several hundred times as that in the MSM, quantitatively. 
Zhou Hong, Ma Wen-Gan, and Zhang Ren-You