The N-Chain Hubbard model in the Composite Operator Method
  We propose a theoretical framework to describe the ladder systems. The N-chain Hubbard model has been studied within the Composite Operator Method. In this scheme of calculations the single-particle Green's function for any number of coupled chains is obtained by solving self-consistently a system of integral equations. 
A. Avella (1), F. Mancini (1), M. M. Sanchez (1) and R. Sridhar (2)   ((1) University of Salerno, Italy; (2) IMSC, Madras, I...