The Small Field Parabolic Flow for Bosonic Many-body Models: Part 3 -   Nonperturbatively Small Errors
  This paper is a contribution to a program to see symmetry breaking in a weakly interacting many Boson system on a three dimensional lattice at low temperature. It is part of an analysis of the "parabolic flow" which exhibits the formation of a "Mexican hat" potential well. Here we provide arguments that suggest, but do not completey prove, that the difference between the "small field" approximation and the full model is nonperturbatively small. 
Tadeusz Balaban, Joel Feldman, Horst Kn\"orrer, Eugene Trubowitz
math-ph math.MP