The O(N) sigma-model Laplacian
arXiv:hep-th/9511041 · doi:10.1016/0370-2693(95)01333-4
Abstract
For fields that vary slowly on the scale of the lightest mass the logarithm of the vacuum functional of a massive quantum field theory can be expanded in terms of local functionals satisfying a form of the Schrödinger equation, the principal ingredient of which is a regulated functional Laplacian. We construct to leading order a Laplacian for the O(N) sigma-model that acts on such local functionals. It is determined by imposing rotational invariance in the internal space together with closure of the Poincaré algebra.
7 pages, latex