Generalised integrable λ - and η -deformations and their relation
Konstantinos Sfetsos (Department of Nuclear and Particle Physics, Faculty of Physics, University of Athens, Athens, 15784, Greece, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern University, Sidlerstrasse 5, Bern, CH3012, Switzerland); Konstantinos Siampos (Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern University, Sidlerstrasse 5, Bern, CH3012, Switzerland); Daniel C. Thompson (Theoretische Natuurkunde, Vrije Universiteit Brussel, The International Solvay Institutes, Pleinlaan 2, Brussels, B-1050, Belgium)
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.
