The complete next-to-next-to-leading order (i.e. O(v2), O(vαs) and O(αs2)) relativistic corrections to the total photon mediated ttˉ production cross section at threshold are presented in the framework of nonrelativistic quantum chromodynamics. The results are obtained using semi-analytic methods and ``direct matching''. The size of the next-to-next-to-leading order relativistic corrections is found to be comparable to the size of the next-to-leading order ones.
@article{arxiv.hep-ph/9801397,
title = {Top Quark Pair Production at Threshold: Complete Next-to-next-to-leading Order Relativistic Corrections},
author = {A. H. Hoang and T. Teubner},
journal= {arXiv preprint arXiv:hep-ph/9801397},
year = {2016}
}