Isotropic Lifshitz critical behavior from the functional renormalization   group
  The Lifshitz critical behavior for a single component field theory is studied for the specific isotropic case in the framework of the Functional Renormalization Group. Lifshitz fixed point solutions of the flow equation, derived by using a Proper Time regulator, are searched at lowest and higher order in the derivative expansion. Solutions are found when the number of spatial dimensions d is contained within the interval 5.5 < d < 8. 
Alfio Bonanno, Dario Zappala
hep-th cond-mat.stat-mech