We construct a resummation at partial next-to-next-to-next-to-leading
logarithmic accuracy for hadronic top-quark pair production near partonic
threshold, including simultaneously soft-gluon and Coulomb corrections, and use
this result to obtain approximate next-to-next-to-next-to-leading order
predictions for the total top-quark pair-production cross section at the LHC.
We generalize a required one-loop potential in non-relativistic QCD to the
colour-octet case and estimate the remaining unknown two-loop potentials and
three-loop anomalous dimensions. We obtain a moderate correction of 1.5%
relative to the next-to-next-to-leading order prediction and observe a
reduction of the perturbative uncertainty below ±5%.Comment: 47 pages, 5 figures, v2: published version, typos corrected
(including scale uncertainties in Eqs. (4.16)-(4.20)), references added; v3:
see added note on p.30 for changes; the results of this work are implemented
in the program TOPIXS, which can be found at
http://users.ph.tum.de/t31software/topixs