Comment on "Mesoscopic Kondo effect in an Aharonov-Bohm ring".

An interacting quantum dot inserted in a mesoscopic ring is investigated. A variational ansatz is employed to describe the ground state of the system in the presence of the Aharonov-Bohm flux. It is shown that, for an even number of electrons with the energy level spacing smaller than the Kondo temperature, the persistent current has a value similar to that of a perfect ring with the same radius. On the other hand, for a ring with an odd number of electrons, the persistent current is found to be strongly suppressed compared to that of an ideal ring, which implies the suppression of the Kondo-resonant transmission. Various aspects of the Kondo-assisted persistent current are discussed.