Based on the construction of Poisson-Lie T-dual σ-models from a common parent action we study a candidate for the non-abelian respectively Poisson-Lie T-duality group. This group generalises the well-known abelian T-duality group O(d, d) and we explore some of its subgroups, namely factorised dualities, B-and β-shifts. The corresponding duality transformed σ-models are constructed and interpreted as generalised (non-geometric) flux backgrounds.We also comment on generalisations of results and techniques known from abelian T-duality. This includes the Lie algebra cohomology interpretation of the corresponding non-geometric flux backgrounds, remarks on a double field theory based on non-abelian T-duality and an application to the investigation of Yang-Baxter deformations. This will show that homogeneously Yang-Baxter deformed σ-models are exactly the non-abelian T-duality β-shifts when applied to principal chiral models.This is an almost para-complex structure because J 2 = 1 and it has d-dimensional ±1eigenbundles. J is chosen in a way, that these eigenbundles are also maximally isotropic subspaces w.r.t. to | . J is integrable as its Nijenhuis-tensorThis opens a new perspective on J: Given a 2d-dimensional Lie algebra with an Ad-invariant O (d, d)-metric, then the choice of a complementary pair of maximally isotropic subspaces w.r.t. to the O(d, d)-metric defines an almost (para-)complex structure J. These subspaces are closed subalgebras, iff the almost (para-)complex structure is integrable. Thus a Manin triple decomposition (d, g, g ) can equivalently be described by the pair (d, J) with an integrable para-complex structure J.The invariance group of the integrability of J is exactly the NATD group (3.1).
Non-degenerate 2-formGiven a metric | and a (para)-complex structure J it is possible to complete a compatible triple (η, J, ω J ) with a non-degenerate two-form ω J via ω J (X, Y) = J(X)|Y . (5.4) c b (∂ − g g −1 ) b .