Non-resonant and electroweak NNLO correction to the e+e− top anti-top threshold.

We determine the NNLO electroweak correction to the e+e−→bb¯¯W+W−X production cross section near the top-pair production threshold. The calculation includes non-resonant production of the final state as well as electroweak effects in resonant top anti-top pair production with non-relativistic resummation, and elevates the theoretical prediction to NNNLO QCD plus NNLO electroweak accuracy. We then study the impact of the new contributions on the top-pair threshold scan at a future lepton collider.