Twisted chiral de Rham complex, generalized geometry, and T-duality

Abstract

The chiral de Rham complex of Malikov, Schechtman, and Vaintrob, is a sheaf of differential graded vertex algebras that exists on any smooth manifold Z , and contains the ordinary de Rham complex at weight zero. Given a closed 3-form H on Z , we construct the twisted chiral de Rham differential D H , which coincides with the ordinary twisted differential in weight zero. We show that its cohomology vanishes in positive weight and coincides with the ordinary twisted cohomology in weight zero. As a consequence, we propose that in a background flux, Ramond–Ramond fields can be interpreted as D H -closed elements of the chiral de Rham complex. Given a T-dual pair of principal circle bundles Z , Zˆ with fluxes H , Hˆ , we establish a degree-shifting linear isomorphism between a central quotient of the i R [ t ] -invariant chiral de Rham complexes of Z and Zˆ . At weight zero, it restricts to the usual isomorphism of S 1 - invariant differential forms, and induces the usual isomorphism in twisted cohomology. This is interpreted as T-duality in type II string theory from a loop space perspective. A key ingredient in defining this isomorphism is the language of Courant algebroids, which clarifies the notion of functoriality of the chiral de Rham complex.