PERIODIC TWISTED COHOMOLOGY AND T-DUALITY

Using the differentiable structure, twisted 2-periodic de Rham cohomology is well known, and showing up as the target of Chern characters for twisted K-theory. The main motivation of this work is a topological interpretation of two-periodic twisted de Rham cohomology which is generalizable to arbitrary topological spaces and at the same time to arbitrary coefficients. To this end we develop a sheaf theory in the context of locally compact topological stacks with emphasis on: - the construction of the sheaf theory operations in unbounded derived categories - elements of Verdier duality - and integration. The main result is the construction of a functorial periodization associated to a U(1)-gerbe. As an application we verify the T-duality isomorphism in periodic twisted cohomology and in periodic twisted orbispace cohomology.