Marginal Fermi liquid behaviour in a coupled quantum dot system

We study the problem of two single-level quantum dots side-coupled to a single site of a one-channel quantum wire, modelling the dots as repulsive Anderson impurities. We study the model within a perturbative approach restricting ourselves to the particle-hole symmetric case and show that it has marginal Fermi liquid properties. Further, we show that the perturbative approach also captures the “singular Fermi liquid physics” characteristic of the underscreened Kondo model expected in the strong-coupling limit. We also predict an underscreened charge Kondo effect for the corresponding model with attractive Anderson interaction.