Two-loop test of Buscher's T duality - art. no. 045005

We study the two loop quantum equivalence of sigma models related by Busche r's T-duality transformation. The computation of the two loop perturbative free energy density is performed in the case of a certain deformation of th e SU(2) principal sigma model, and its T dual, using dimensional regulariza tion and the geometric sigma model perturbation theory. We obtain agreement between the free energy density expressions of the two models.