Duality for coset models

We construct dual Lagrangians for G/H models in two space-time dimensions for arbitrary Lie Groups G and H subset of G. Our approach does not require choosing coordinates on G/H, and allows for a natural generalization to Poisson-Lie T-duality. For the case where the target metric on G/H is induced from the invariant group metric on G, the dual system is a gauged Higgs model, with a non-constant metric and a coupling to an antisymmetric tensor. The dynamics for the gauge connection is governed by a BF-term. Poisson-Lie T-duality is relevant once we allow for a more general class of target metrics, as well as for couplings to an antisymmetric tensor, in the primary theory. Then the dual theory is written on a group (G) over tilde dual to G, and the gauge group H (which, in general, is not a subgroup of (G) over tilde) acts non-linearly on (G) over tilde. The dual system therefore gives a non-linear realization of a gauge theory. All dual descriptions are shown to be canonically equivalent to the corresponding primary descriptions, at least at the level of the current algebra. (C) 1999 Elsevier Science B.V. All rights reserved.