  We study non conventional superconductivity on a ladder, improving the
predictions of the Hubbard model. The determination of the Fermi surface, in 2
or 3 dimensions, remains a very hard task, but it is exactly solvable for a
single ladder. We use functional Renormalisation Group methods, which prove,
here, scheme-dependant. In the superconducting phase, the binding/antibinding
gap is stabilized, but in the antiferromagnetic phase, it shrinks and the
ladder turns one-dimensional.
