Dualised sigma-models at the two-loop order

Abstract

We adress ourselves the question of the quantum equivalence of non abelian dualised $\si$-models on the simple example of the T-dualised $SU(2) \si$-model. This theory is classically canonically equivalent to the standard chiral $SU(2) \si$-model. It is known that the equivalence also holds at the first order in perturbations with the same $\be$ functions. However, this model has been claimed to be non-renormalisable at the two-loop order. The aim of the present work is the proof that it is - at least up to this order - still possible to define a correct quantum theory. Its target space metric being only modified in a finite manner, all divergences are reabsorbed into coupling and fields (infinite) renormalisations.