Existence of Long-Range Order in Quasi-Two-Dimensional Hubbard Model

A. Belkasri, J. L. Richard

In recent work of Monthoux and Pines~[1] and also in Rice et {\sl al.}'s work~[2], quasi-averages like $⟨c_{k\uparrow }{c}_{-k\downarrow }⟩$ were considered even in t…