Is the quantum dot at large bias a weak-coupling problem?
  We examine the two-lead Kondo model for a d.c. biased quantum dot in the Coulomb blockade regime. From perturbative calculations of the magnetic susceptibility, we show that the problem retains its strong-coupling nature, even at bias voltages larger than the equilibrium Kondo temperature. We give a speculative discussion of the nature of the renormalization group flows and the strong-coupling state that emerges at large voltage bias. 
P. Coleman (Rutgers), C. Hooley (Rutgers and Birmingham), O. Parcollet   (Rutgers)