Integrability vs. RG flow in G × G and G × G/H sigma models

Abstract

We consider a class of 2d σ-models on products of group spaces that provide new examples of a close connection between integrability and stability under the RG flow. We first study the integrable G × G model derived from the affine Gaudin construction (for which the 1-loop β-functions were found in arXiv:2010.07879) and show that its condition of integrability is preserved also by the 2-loop RG flow. We then investigate the RG flow in the gauged G × G/H model, in particular the integrable T1,1 model found in arXiv:2010.05573. We also construct a new class of integrable G × G/H models in the case when the subgroup H is abelian. In the simplest case of G = SU2, H = U1 this leads to an integrable σ-model on the T1,q space (with a particular B-field). This model is also shown to be stable under the 2-loop RG flow, and we relate this property to its invariance under T-duality in an isometric U1 direction. This T1,q model may be interpreted as an integrable deformation of the GMM model (of two coupled WZW theories with generic levels) away from the conformal point.

Integrable deformed T1,1 sigma models from 4D Chern-Simons theory

“…This is nothing but the Lagrangian and Lax pair of a G × G/H sigma model related to the tripled G/H λ-model formulation 4 [54,55] . Notably, in the limit z 1 /z 2 → 0, the action (3.65) reduces to that of the GMM model [52].…”