The Fermi liquid nature of the ground state of double quantum dots in   parallel from a 1/N expansion
  A large-N diagrammatic approach is used to study coupled quantum dots in a parallel geometry. We show that the Friedel sum rule (FSR) holds at lowest order in a 1/N expansion for this system, thereby suggesting that the ground state is a Fermi liquid. Using the FSR together with the dot occupancy, we compute the dot system's conductance. Our finding that the 1/N expansion indicates the system is a Fermi liquid is in agreement with both prior results based on the Bethe ansatz and slave boson mean field theory. 
Manas Kulkarni and Robert Konik
cond-mat.mes-hall