Top quark production near threshold: NNLO QCD correction

We calculate the cross section of the process e+e−→tt̄ near threshold by resumming Coulomb-like terms with next-to-next-to-leading (NNLO) accuracy. The nonrelativistic Green function formalism and the method of “direct matching” are used. The NNLO correction turns out to be large, of the same size as the NLO correction. It changes the position and the normalization of the 1S-peak. The obtained results are compared with results existing in the literature.