====== TTP08-43 ${\cal O}(\alpha\alpha_s)$ corrections to the $\gamma t\bar{t}$ vertex at the top quark threshold ====== We compute the last missing piece of the two-loop ${\cal O}(\alpha \alpha_s)$ corrections to $\gamma t \bar{t}$ vertex at the $t \bar{t}$ threshold due to the exchange of a $W$ boson and a gluon. This contribution constitutes a building block of the top quark threshold production cross section at electron positron colliders. |**Yuichiro Kiyo, Dirk Seidel, Matthias Steinhauser** | |** JHEP 0901 038 2009 ** | | {{preprints:2008:ttp08-43.pdf|PDF}} {{preprints:2008:ttp08-43.ps|PostScript}} [[http://arxiv.org/abs/0810.1597|arXiv]] [[http://ttp.kit.edu/Progdata/ttp08/ttp08-43|Programs and Data]] | | |