T-duality for principal torus bundles and dimensionally reduced Gysin sequences
Peter Bouwknegt, Keith Hannabuss, Varghese Mathai
TL;DR
This work develops a global framework for T-duality of principal torus bundles with NS $H$-flux by constructing a dimensionally reduced Gysin sequence via the Chern-Weil mechanism. It shows that the T-dual is generically a continuous field of noncommutative, nonassociative tori over the base, classified by a 3‑tuple of flux components and dual curvature data, with the $O(n,n;\mathbb{Z})$ duality group acting linearly on the associated invariants. Twisted cohomology and a dimensionally reduced Gysin sequence underpin the duality, providing explicit maps and exact sequences that connect base and total space data. The results extend Buscher rules from circles to higher-rank tori and reveal deep connections to operator algebraic constructions, suggesting a rich geometry of T-duals beyond classical bundle theories. The findings offer a path toward manifestly T-duality-invariant descriptions in string theory that naturally incorporate noncommutative and nonassociative structures.
Abstract
We reexamine the results on the global properties of T-duality for principal circle bundles in the context of a dimensionally reduced Gysin sequence. We will then construct a Gysin sequence for principal torus bundles and examine the consequences. In particular, we will argue that the T-dual of a principal torus bundle with nontrivial H-flux is, in general, a continuous field of noncommutative, nonassociative tori.
