Top quark pair production via (un)polarized photon collisions in the   littlest Higgs model with T-parity at the ILC
  We study the top-quark pair production via polarized and unpolarized photon collisions at the International Linear Collider in the context of the littlest Higgs model with T-parity. We calculate the production cross section of the process $\gamma\gamma\rightarrow t\bar{t}$ and find the effects can be more significant in the $- -$ polarized photon collision mode than in other collision modes, and the relative correction can be expected to reach about -1% in the favorable parameter space. 
Bingfang Yang
hep-ph