2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/22287We use exact diagonalization to determine the spectrum of reduced Hamiltonians based on renormalization group flows to strong coupling. For the half-filled two-leg Hubbard ladder we reproduce the known insulating d-Mott groundstate with spin and charge gaps. For the saddle point regions of the two-dimensional Hubbard model near half-filling we find a crossover to a similar strong coupling state, which truncates the Fermi surface near the saddle points. At lower scales d-wave superconductivity appears on the remaining Fermi surface.4 pages, 4 figures, published version, journal reference addedStrongly Correlated ElectronsSuperconductivitytext