Quantum Critical Behavior of Disordered Superfluids
  The quantum critical behavior of an interacting, non-relativistic Bose theory with quenched disorder randomly distributed in space is investigated. The renormalization group is carried out in a double $\epsilon$ expansion, where one $\epsilon$ is the deviation of the effective space-time dimensionality from 4, while the other denotes the number of time dimensions. The disordered theory, which displays localization in the superfluid state, is shown to possess an infrared stable fixed point. 
Adriaan M. J. Schakel