Exact solution of a one-dimensional fermion model with interchain   tunneling
  A fermion model consisting of two chains with interchain tunneling is formulated and solved exactly by the Bethe ansatz method. The interchain tunneling leads to Cooper pair like bound states and a threshold energy is required to overcome the binding energy. The correlation functions manifest superconducting properties. 
R. Z. Bariev, A. Kl\"umper, A. Schadschneider, and J.Zittartz