Abstract

Non-Abelian T-duality (NATD) is a solution generating transformation for supergravity backgrounds with non-Abelian isometries. We show that NATD can be de-scribed as a coordinate dependent O(d,d) transformation, where the dependence on the coordinates is determined by the structure constants of the Lie algebra associated with the isometry group. Besides making calculations significantly easier, this approach gives a natural embedding of NATD in Double Field Theory (DFT), a framework which provides an O(d,d) covariant formulation for effective string actions. As a result of this embedding, it becomes easy to prove that the NATD transformed backgrounds solve supergravity equations, when the isometry algebra is unimodular. If the isometry algebra is non-unimodular, the generalized dilaton field is forced to have a linear dependence on the dual coordinates, which implies that the resulting background solves generalized supergravity equations.

Highlights

  • A compact formula for the transformation of the supergravity fields for a generic Green-Schwarz string with isometry G has been obtained in [17], where they showed that the sigma model after Non-Abelian T-duality (NATD) has kappa symmetry

  • The dependence on the coordinates is determined by the structure constants of the Lie algebra associated with the isometry group

  • As a result of this embedding, we managed to prove that the NATD fields solve supergravity equations, when the isometry algebra is unimodular

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Summary

Transformation of the fields in the NS-NS sector

Let g and B be the metric and the Kalb-Ramond 2-form field that describes a D dimensional supergravity background, with d commuting isometries. Let us decompose the background matrix with respect to this choice of coordinates as. Define (along with the transformed dilaton field we will discuss below, see (2.10)) valid supergravity backgrounds. The O(D, D, R) transformation defined above acts as a solution generating transformation. Let us write the final form of the transformed background matrix Q : E (a − E c)F 2. For the resulting background to be a valid supergravity solution, the dilaton field φ should transform under O(D, D, R) in the following way: e−2φ = e−2φ detG detG (2.10). It is checked from (2.10) that e−2d = e−2d under O(D, D).

Transformation of the fields in the RR sector
An example
NATD as a solution generating transformation in Double Field Theory
A brief review of Double Field Theory
Embedding NATD in Double Field Theory
Gauged Double Field Theory
Fluxes associated with the NATD matrix
Comparing the field equations of DFT and GDFT
Field equations for the generalized dilaton field
Field equations for the generalized metric HMN
NATD fields as a solution of DFT in the supergravity frame
Non-unimodular case: generalized supergravity equations
Conclusions and outlook
A Index conventions
Full Text
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