Rational conformal field theories at, and away from, criticality as Toda field theories

Abstract

Abstract Recently, Zamolodchikov has shown that certain minimal conformal field theories preserve their integrability away from the critical point. In an attempt to understand these results we consider a class of integrable field theories, namely two-dimensional Toda field theories. It is found that for particular values of the coupling constant these theories describe minimal models, in particular the Ising model can be described both by an E 8 and A 1 Toda field theory. The affine versions of these theories then represent the model away from criticality, for instance the Ising model in a magnetic field is described by the affine E 8 Toda field theory, whereas the affine A 1 theory describes a thermal perturbation. This generalizes to a deformation of all minimal models.