The Orbital Selective Mott Transition in a Three Band Hubbard model: a   Slave Boson Mean Field Study
  In the present paper, we systematically studied the possible Orbital selective Mott transition (OSMT) in the $t_{2g}$ system, which has three orbital degeneracy. The slave Boson mean field theory is generalized to the three band systems with full Hund's rule coupling including spin flip and pair hopping terms. A new type of Mott transition which is driven by the crystal field splitting or the lattice distortion is found is this model. We argue that this new type of Mott transition may relate to the puzzling phase in $Sr_{x}Ca_{2-x}RuO_4$. 
Xi Dai, Gabriel Kotliar, Zhong Fang