Matching Threshold and Continuum for Exclusive Top Pairs

The threshold scan at future lepton colliders is the most preciseknown method to determine the top quark mass (well below 100 MeV), afundamental parameter of the Standard Model that co-determines thestability properties of the electroweak vacuum. We present a new method tomatch the continuum next-to-leading order QCD corrections with thenext-to-leading logarithmic resummation of the Coulomb singularities of thequasi-toponium bound state at threshold where fixed-order perturbationtheory is invalid. This matching is performed at the level of the fullyexclusive WbWb final state. It allows to study all kinds of differentialdistributions at or close to threshold. The top mass dependence of thesedistributions opens up new possibilities for the top mass determinationthat might be competitive with the inclusive threshold scan