Cooper pairing at large N in a two-dimensional model

We study a two-dimensional model of fermi fields psi that is closely relate d to the Gross-Neveu model, and show that to leading order in 1/N a [psi ps i] condensate forms. This effect is independent of the chemical potential, a peculiarity that we expect to he specific to two dimensions. We also expe ct the condensate to be unstable against corrections at higher orders in 1/ N. We compute the Green's functions associated with the composite psi psi, and show that the fermion acquires a Majorana mass proportional to the gap, and that a massless Goldstone pole appears. (C) 1999 Elsevier Science B.V. All rights reserved.