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Global Aspects of T-Duality, Gauged Sigma Models and T-Folds

C. M. Hull
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Abstract

The gauged sigma-model argument that string backgrounds related by T-dual give equivalent quantum theories is revisited, taking careful account of global considerations. The topological obstructions to gauging sigma-models give rise to obstructions to T-duality, but these are milder than those for gauging: it is possible to T-dualise a large class of sigma-models that cannot be gauged. For backgrounds that are torus fibrations, it is expected that T-duality can be applied fibrewise in the general case in which there are no globally-defined Killing vector fields, so that there is no isometry symmetry that can be gauged; the derivation of T-duality is extended to this case. The T-duality transformations are presented in terms of globally-defined quantities. The generalisation to non-geometric string backgrounds is discussed, the conditions for the T-dual background to be geometric found and the topology of T-folds analysed.

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C. M. Hull. 2007-09-28. Global Aspects of T-Duality, Gauged Sigma Models and T-Folds. https://doi.org/10.1088/1126-6708%2F2007%2F10%2F057

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