Generalised integrable λ- and η-deformations and their relation.

We construct two-parameter families of integrable λ -deformations of two-dimensional field theories. These interpolate between a CFT (a WZW/gauged WZW model) and the non-Abelian T-dual of a principal chiral model on a group/symmetric coset space. In examples based on the SU ( 2 ) WZW model and the SU ( 2 ) / U ( 1 ) exact coset CFT, we show that these deformations are related to bi-Yang–Baxter generalisations of η -deformations via Poisson–Lie T-duality and analytic continuation. We illustrate the quantum behaviour of our models under RG flow. As a byproduct we demonstrate that the bi-Yang–Baxter σ -model for a general group is one-loop renormalisable. [ABSTRACT FROM AUTHOR]