The Pseudogaps of HTSC

The problem of the pseudogaps in oxide HTSC is analyzed by means of the off-diagonal propagators, in analogy with the method of Nambu in superconductivity. We conjecture that the small pseudogap is obtained as the Fock diagram and the large pseudogap as the total off-diagonal self-energy (which is the sum of the Hartree diagram and the Fock diagram). We obtain real gap for undoped materials, and pseudogaps (with states in the gap) for doped and conducting materials. We find that disorder is essential for the results of the doped materials.