Resonant Andreev Tunneling in Strongly Interacting Quantum Dots

We study resonant Andreev tunneling through a strongly interacting quantum dot connected to a normal and to a superconducting lead. We obtain a formula for the Andreev current and apply it to discuss the linear and nonlinear transport in the nonperturbative regime, where the effects of the Kondo resonance on the two-particle tunneling arise. In particular, we notice an enhancement of the Kondo anomaly in the $I-V$ characteristics due to the superconducting electrode.