Toric generalized Kaehler structures

Abstract

Anti-diagonal toric generalized K$\ddot{a}$hler structures of symplectic type on a compact toric symplectic manifold were investigated in \cite{Wang2} . In this article, we consider \emph{general} toric generalized K$\ddot{a}$hler structures of symplectic type, without requiring them to be anti-diagonal. Such a structure is characterized by a triple $(\tau, C, F)$ where $\tau$ is a strictly convex function defined in the interior of the moment polytope $\Delta$ and $C, F$ are two constant anti-symmetric matrices. We prove that underlying each such a structure is a \emph{canonical} toric K$\ddot{a}$hler structure $I_0$ whose symplectic potential is given by this $\tau$, and when $C=0$ the generalized complex structure $\mathbb{J}_1$ other than the symplectic one arises from an $I_0$-holomorphic Poisson structure $\beta$ in a \emph{novel} way not mentioned in the literature before. Conversely, given a toric K$\ddot{a}$hler structure with symplectic potential $\tau$ and two anti-symmetric constant matrices $C, F$, the triple $(\tau, C, F)$ then determines a toric generalized K$\ddot{a}$hler structure of symplectic type canonically if $F$ satisfies additionally a certain positive-definiteness condition. In particular, if the initial toric K$\ddot{a}$hler manifold is the standard $M_\Delta$ associated to a Delzant polytope $\Delta$, the resulting generalized K$\ddot{a}$hler structure can be interpreted as obtained via generalized K$\ddot{a}$hler reduction from a generalized K$\ddot{a}$hler structure on an open subset of a complex linear space, just as in Delzant's construction $M_\Delta$ is obtained through K$\ddot{a}$hler reduction from a complex linear space.