Light Fermion Finite Mass Effects in Non-relativistic Bound States
  We present analytic expressions for the vacuum polarization effects due to a light fermion with finite mass in the binding energy and in the wave function at the origin of QED and (weak coupling) QCD non-relativistic bound states. Applications to exotic atoms, \Upsilon (1s) and t\bar{t} production near threshold are briefly discussed. 
Dolors Eiras and Joan Soto