We provide a new construction of the dressing cosets σ-models which is based on an isotropic gauging of the E-models. As an application of this new approach, we show that the recently constructed multiparametric integrable deformations of the principal chiral model are the dressing cosets, they are therefore automatically renormalizable and their dynamics can be completely characterised in terms of current algebras.
Keywords: integrable sigma models, renormalization group flowRecently, Delduc, Hoare, Kameyama and Magro have found the multi-parametric integrable σ-model (1.1) living on an arbitrary simple group manifold K [15]. In their approach, they succeeded to merge consistently several deformation procedures studied previously in a separate way, like the (bi)-Yang-Baxter deformations [44], the addition of the WZW term [17] or the introduction of the so-called TsT matrix [29,59,62,66,80]. For the special case of the group SU (2), their result fits into the framework of the Lukyanov model [58].We show in Section 4 of the present paper that there exists an E-model description of the DHKM σ-model (for the emancipated parameter α), however, there is a novel element in the game comparing with the cases of the low number of deformation parameters treated in [45,46]. Namely, the E-model 1 The reason for this terminology is the fact that in the case α = 0 we recover from (1.9) the standard WZW model. In what follows, we shall say "the DHKM model" whenever the TsT matrix is switched on. However, for the case of the vanishing TsT matrix we reserve the terminology "the bi-YB-WZ model".underlying the DHKM σ-model turns out to be degenerate, that is, it is the so called dressing coset in the sense of Ref. [51].Actually, we introduce in the present work a new method of constructing the dressing cosets which is based on an appropriate isotropic gauging of the non-degenerate E-models. This new approach is technically very friendly and it plays the key role in the understanding of the structure of the DHKM model. We describe it in Section 3.3, just after reviewing the theory of the non-degenerate E-models in Section 3.1 as well as the old theory of the dressing cosets in Section 3.2.What is it good for to know that the first order Hamiltonian dynamics of a nonlinear σ-model can be described in terms of a particular (degenerate) E-model? Well, the immediate benefit of this knowledge is the fact that the σ-model underlied by the E-model is automatically renormalizable [74,76,79]. This means, in particular, that the ultraviolet corrections just let flow the parameters of the model without spoiling the form of the Lagrangian. Moreover, the E-model formalism permits to determine the renormalization group flow by a simple method introduced in Ref. [70,76]. Actually, we employ this method in Section 6 to establish the renormalizability of the bi-YB-WZ model, after proving in Section 5 its integrability. Finally, we devote Section 6.4 to a detailed analysis of the case of K = SU (2) where our results for the bi-YB-WZ RG flow are shown...