QCD interactions. The new corrections show interesting features. They slightly modify the form of the cross section line-shape and lead to UV phase space divergences that are directly related to the fact that the top quarks are unstable. The divergences lead to anomalous dimensions of $(e^+e^-)(e^+e^-)$ operators that also contribute to the absorptive part of the forward scattering amplitude. In the total cross section these mixing effects contribute at NLL order and represent a novel NLL effect that has remained unnoticed in previous work. Numerically, the size of the new corrections ranges up to 5% and partly compensates for the large QCD corrections found recently in [@Hoang3loop].

The program of this paper is as follows. In Sec.\[sectionpowercounting\] we discuss the power counting for the total cross section with respect to electroweak effects associated with the top quark decay. We introduce the $(e^+e^-)(t\,\bar t)$ effective theory operators needed to account for the electroweak absorptive parts that arise in top pair production or annihilation. In particular, we show that up to NNLL order there are no contributions from interference effects originating from (ultrasoft) gluons carrying momenta of order $m_t v^2$. In Sec.\[sectionmatchingconditions\] the electroweak absorptive parts of the matching conditions for the 