Abstract

Double Field Theory is a manifestly T-duality invariant formulation of string theory in which the effective theory at any order of $\alpha'$ is invariant under global $O(D,D)$ transformations and ought to be invariant under gauge transformations which receive $\alpha'$-corrections. On the other hand, the effective theory in the usual $D$-dimensional formulation of string theory is manifestly gauge invariant and ought to be invariant under T-duality transformations which receive $\alpha'$-corrections. We speculate that the combination of these two constraints may fix both the $2D$-dimensional and the $D$-dimensional effective actions without knowledge of the $\alpha'$-corrections of the gauge and the T-duality transformations. In this paper, using generalized fluxes, we construct arbitrary $O(D,D)$-invariant actions at orders $\alpha'^0$ and $\alpha'$, and then dimensionally reduce them to the $D$-dimensional spacetime. On the other hand, at these orders, we construct arbitrary covariant $D$-dimensional actions. Constraining the two $D$-dimensional actions to be equal up to non-covariant field redefinitions, we find that both actions are fixed up to overall factors and up to field redefinitions.

Highlights

  • One of the most exciting discoveries in string theory is T-duality [1,2]

  • The double field theory (DFT) is a constraint field theory which doubles the spacetime coordinates, i.e., adds to the usual D-dimensional spacetime coordinates which correspond to the momentum excitations, another D-dimensional coordinates which correspond to the winding excitations

  • Since the field redefinitions freedom is not fixed in the 2D-dimensional action, we have found the 2D-dimensional action with some arbitrary parameters

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Summary

INTRODUCTION

One of the most exciting discoveries in string theory is T-duality [1,2]. This duality may be used to construct the effective field theory at low energy. Another T-duality based approach for constructing the effective action at higher orders of α0, is to use the constraint that the dimensional reduction of the effective action on a circle must be invariant under the T-duality transformations [12] In this approach, one begins with the most general gauge invariant action in the D-dimensional spacetime. (2) After reducing it to the D-dimensional spacetime and using noncovariant field redefinitions, the action is constrained to be the same as a D-dimensional action which is invariant under the standard coordinate transformations, the B-field gauge transformations and the nonstandard Lorentz transformation of the B-field, it is not invariant under the T-duality transformations which receive α0-corrections. Using the generalized fluxes, we first construct the most general OðD; DÞ-invariant action at order α0 without fixing its field redefinitions freedom, and reduce it to the D-dimensional action. In one particular scheme in which dilaton appears as an overall factor, we write the effective action

EFFECTIVE ACTION AT ORDER α00
Generalized metric formulation
Generalized frame formulation
EFFECTIVE ACTION AT ORDER α0
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