Bloch Theory for Periodic Block Spin Transformations
  Block spin renormalization group is the main tool used in our program to see symmetry breaking in a weakly interacting many Boson system on a three dimensional lattice at low temperature. It generates operators, like the fluctuation integral covariance, that act on some lattice but are translation invariant only with respect to a proper sublattice. This paper constructs a Bloch/Floquet framework that is appropriate for bounding such operators. 
Tadeusz Balaban, Joel Feldman, Horst Kn\"orrer, Eugene Trubowitz
math-ph math.MP