New mean field theory of the tt't''J model applied to the high-Tc   superconductors
  We introduce a new mean field approach to the tt't''J model that incorporates both electron-like quasiparticle and spinon excitations as suggested by some experiments and numerical studies. It leads to a mean field phase diagram which is consistent with that of hole and electron doped cuprates. Moreover, it provides a framework to describe the observed evolution of the electron spectral function from the undoped insulator to the overdoped Fermi metal for both hole and electron doping. The theory also provides a new non-BCS mechanism leading to superconductivity. 
Tiago C. Ribeiro, Xiao-Gang Wen