these specific NLL contributions in Sec.\[sectionrenormalization\] and ignore them for the following considerations. Thus, concerning NLL effects related to the top decay only the one-loop QCD corrections to the on-shell top decay width have to be accounted for [@Jezabek1]. In particular, there are no QCD interference effects from gluon radiation off the top/antitop quark or its decay products[@Fadin2; @Melnikov1]. In our approach, which only aims at the total cross section, one can show that such QCD interference effects do not even contribute at NNLL order in the non-relativistic expansion.

To discuss the QCD interference contributions we have to consider ultrasoft gluons, which carry momenta of order $m_t v^2\sim\Gamma_t$, because they can interact with a resonant top quark without kicking it off-shell. For the time-like $A^0$ gluons we already mentioned that their leading interaction with the quarks can be removed by a field redefinition related to static Wilson lines [@Korchemsky1; @Bauer1]. Moreover, QCD gauge invariance ensures that the dominant electroweak matching corrections to the $A^0$ interaction vertex vanish because we can set the ultrasoft gluon momentum to zero. Radiative corrections can, however, generate an anomalous interaction in analogy to the $g-2$ in QED. Yet this interaction is suppressed by a factor 