From QCD Strings to WZW

According to the Axionic String Ansatz (ASA) confining flux tubes in pure gluodynamics are in the same equivalence class as a new family of integrable non-critical strings, called axionic strings. In addition to translational modes, axionic strings carry a set of worldsheet axions transforming as an antisymmetric tensor under the group of transverse rotations. We initiate a study of integrable axionic strings at general number of space-time dimensions D. We show that in the infinite tension limit worldsheet axions should be described by a peculiar "pseudofree" theory — their S-matrix is trivial, but the corresponding action cannot be brought into a free form by a local field redefinition. This requirement fixes the axionic action to take a form of the O(D − 2) Wess-Zumino-Witten (WZW) model.