Heavy top renormalon contribution to fermion propagators
  We study resummed perturbative contributions due to a heavy top-quark. These renormalon contributions are evaluated for fermion propagators. Results for the top-quark width are given. Estimates of non-perturbative uncertainties are made on the \rho-parameter using different schemes of dealing with the Landau-pole. For the physical top-quark mass the effects are negligible. 
D. Bettinelli and J. J. van der Bij
hep-ph hep-th