Impact of Coulomb interaction and Kondo effect on transport in quantum dots

We examine the impact of Coulomb electron-electron interaction on transport in a junction with a quantum dot described by the Kondo Hamiltonian. We analyze the Fermi-liquid regime and consider the limit of zero temperature. With the help of the Keldysh technique, we calculate the nonlinear current and shot noise as a function of applied voltage. We show that Coulomb interaction remarkably influences the universal effective charge of current-carrying particles e* =5 3e, which can be measured in shot-noise experiments. The electron-electron interaction modifies this universal value by a factor (e* =5 3eF) which is less than 1 and also voltage dependent.