In this paper we deal with the linear O(N) σ-model in four dimensions in the broken phase. It is argued that the zero-momentum two-point function in a finite box obeys a soft-pion finite-size theorem which holds if the boundary conditions are periodic. The theorem's validity depends only on the structure of the would-be massless sector of the model.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics