T-duality for toric manifolds in $\mathcal{N}=(2, 2)$ superspace
Dmitri Bykov, Savva Kutsubin, Andrew Kuzovchikov
TL;DR
The paper establishes that T-duality for toric Kähler manifolds in $ ext{N}=(2,2)$ superspace generically yields generalized Kähler geometries in the dual frame when multiple isometries act in a way that is not a symmetry of the Kähler potential. To gauge these isometries, the authors introduce an enlarged gauge multiplet $(oldsymbol{V},oldsymbol{X})$ that includes a semi-chiral field, enabling a coherent dualization and accounting for cross-terms that encode nontrivial topology, such as a fixed imaginary period (e.g., $oldsymbol{T} o oldsymbol{T}+i/4$). Applying the construction to the $oldsymbol{ ext{C}}^ imes imes oldsymbol{ ext{C}}^ imes$ model and to the $ ext{CP}^{n-1}_{oldsymbol{ abla}}$ eta-deformed model, the dual geometries are explicit: the dual of $ ext{CP}^{n-1}_{oldsymbol{ abla}}$ is Kähler, while the original is generalized Kähler, with the Legendre transform yielding the symplectic potential governing the dual geometry. In the $oldsymbol{ ho} o0$ (undeformed) limit, both frames reduce to Kähler manifolds, connecting with familiar toric/Hilbert-space dualities and providing a concrete, algorithmic approach to construct dual generalized Kähler backgrounds in 2D supersymmetric sigma models.
Abstract
We study the situation when the T-dual of a toric Kähler geometry is a generalized Kähler geometry involving semi-chiral fields. We explain that this situation is generic for polycylinders, tori and related geometries. Gauging multiple isometries in this case requires the introduction of semi-chiral gauge fields on top of the standard ones. We then apply this technology to the generalized Kähler geometry of the $η$-deformed $\mathbb{CP}^{n-1}$ model, relating it to the Kähler geometry of its T-dual.
