A fully fermionic mean field theory of the cuprate superconductors

We introduce a new, fully fermionic, mean field approach to the extended $tJ$ model, which incorporates both hole-like quasiparticle and spin-charge separated excitations, and argue that it is relevant to both hole and electron doped cuprates. We show this approach leads to a mean field phase diagram that closely resembles the one of the cuprate materials and compare it to additional experimental evidence. This theory provides a new non-BCS mechanism leading to superconductivity.