NNNLO soft-gluon corrections for the top-antitop pair production cross section

I present a calculation of next-to-next-to-next-to-leading-order (NNNLO) soft-gluon corrections for top-antitop pair production in hadronic collisions. Approximate NNNLO (aNNNLO) results are obtained by adding the NNNLO soft-gluon corrections to the complete next-to-next-to-leading-order (NNLO) cross section. Theoretical predictions are shown for the total aNNNLO t(t) over bar cross section at LHC and Tevatron energies. The aNNNLO cross sections are larger but have smaller theoretical uncertainties than at NNLO.