Poster presented by Oleg Borisenko

Topic: Spin Models

Two-dimensional lattice SU(N) spin models in the low-temperature limit

Abstract: We use an invariant link formulation of SU(N) spin models on the lattice to investigate some of their properties in two dimensions. Emphasis is put on the properties of the low-temperature expansion in this formulation. In particular, we prove that this expansion coincides with the conventional perturbation theory (PT) and establish some general properties of this expansion. Unlike the conventional PT our method gives a possibility to investigate the infrared finitness of the remainder to the finite-volume weak coupling expansion and thus to answer the principal question regarding the uniformity of the PT in the volume. Further, we calculate non-abelian analog of the spin-wave--vortex representation for the partition function which allows to study analytically long-range properties of non-abelian models in a trustable way.

Massimo Campostrini, campo@mailbox.difi.unipi.it