Backward Scattering and Coexistent State in Two-Dimensional Electron   System
  The results of the mean field studies on the effects of the backward scattering with large momentum transfer in a two-dimensional electron system are extended to the case with various types of the Fermi surface and coupling constants. It is found that the coexistent state of d-wave superconductivity, antiferromagnetism and $\pi$-triplet pair can be stabilized quite generally near half filling. 
Masakazu Murakami (1), Hidetoshi Fukuyama (1) ((1) Tokyo University)