Interband pairing in extended two- and three-band Hubbard model

We study the existence of intraband and interband pairing in the extended two band and three-band Hubbard model. It is shown that including interband pairing significantly increases the superconducting critical temperature in comparison with critical temperature of the intraband pairing. This increase allows for decrease of the nearest-neighbor interaction constant necessary for critical temperature in high temperature superconductors to the realistic values.