Yolanda Lozano

Some global aspects of duality in string theory

Abstract We explore some of the global aspects of duality transformations in String Theory and Field Theory. We analyze in some detail the equivalence of dual models corresponding to different topologies at the level of the partition function and in terms of the operator correspondence for abelian duality. We analyze the behavior of the cosmological constant under these transformations. We also explore several examples of non-abelian duality where the classical background interpretation can be maintained for the original and the dual theory. In particular, we construct a non-abelian dual of SL(2, R ) which turns out to be a three-dimensional black hole.

On Non-Abelian Duality

A general study of non-abelian duality is presented. We first identify a possible obstruction to the conformal invariance of the dual theory for non-semisimple groups. We construct the exact non-abelian dual for any Wess-Zumino-Witten (WZW) model for any anomaly free subgroup, and the corresponding extension for coset conformal field theories. We characterize the exact non-abelian dual for σ-models with chiral isometries and extend the standard notion of duality to anomalous subgroups of WZW-models, thus giving a way of constructing dual transformations for different groups on the left and on the right. We also present some new examples of non-abelian duality for four-dimensional gravitational instantons.

A Canonical approach to duality transformations

Abstract We show that Buschers Abelian duality transformation rules can be recovered in a very simple way by performing a canonical transformation first suggested by Giveon, Rabinovici and Veneziano. We explore the properties of this transformation, and also discuss some aspects of non-Abelian duality.

Supersymmetric AdS(6) via T Duality

We present a new supersymmetric AdS(6) solution of type IIB supergravity with SU(2) isometry. Through the AdS/CFT correspondence, this has potentially very interesting implications for 5D fixed point theories. This solution is the result of a non-Abelian T duality on the known supersymmetric AdS(6) solution of massive IIA. The SU(2) R symmetry is untouched, leading to sixteen supercharges and preserved supersymmetry.

Non-abelian T-duality, Ramond fields and coset geometries

We extend previous work on non-abelian T-duality in the presence of Ramond fluxes to cases in which the duality group acts with isotropy such as in backgrounds containing coset spaces. In the process we generate new supergravity solutions related to D-brane configurations and to standard supergravity compactifications.

A Microscopical Description of Giant Gravitons

Abstract We construct a non-Abelian world volume effective action for a system of multiple M-theory gravitons. This action contains multipole moment couplings to the eleven-dimensional background potentials. We use these couplings to study, from the microscopical point of view, giant graviton configurations where the gravitons expand into an M2-brane, with the topology of a fuzzy 2-sphere, that lives in the spherical part of the AdS7×S4 background or in the AdS part of AdS4×S7. When the number of gravitons is large we find perfect agreement with the Abelian, macroscopical, description of giant gravitons given in the literature.

Hints of 5d fixed point theories from non-Abelian T-duality

A bstractIn this paper we investigate the properties of the putative 5d fixed point theory that should be dual, through the holographic correspondence, to the new supersymmetric AdS6 solution constructed in [1]. This solution is the result of a non-Abelian T-duality transformation on the known supersymmetric AdS6 solution of massive Type IIA. The analysis of the charge quantization conditions seems to put constraints on the global properties of the background, which, combined with the information extracted from considering probe branes, suggests a 2-node quiver candidate for the dual CFT.

Non-abelian T-duality and consistent truncations in type-II supergravity

A bstractFor a general class of SO(4) symmetric backgrounds in type-II supergravity, we show that the action of non-Abelian T-duality can be described via consistent truncation to seven dimensional theories with seemingly massive modes. As such, any solution to these theories uplifts to both massive type IIA and IIB supergravities presenting an invertible map between the two. For supersymmetric backgrounds, we show that for spinors transforming under SO(4) the non-Abelian T-duality transformation breaks the original supersymmetry by half. We use these mappings to generate the non-Abelian T-duals of the maximally supersymmetric pp-wave, the Lin, Lunin, Maldacena geometries and spacetimes with Lifshitz symmetry.

Supersymmetry and non-Abelian T-duality in type II supergravity

We study the effect of T-duality on supersymmetry in the context of type II supergravity. For both U(1) Abelian and SU(2) non-Abelian T-duality, we demonstrate that the supersymmetry variations after T-duality are related to the variations before T-duality through the Kosmann spinorial Lie derivative, which vanishes when the Killing spinors are independent of the T-duality directions. As a byproduct of our analysis, we present closed expressions for SU(2) T-duality in a class of spacetimes with diagonal Bianchi IX symmetry and comment on specific examples of T-dual geometries, including a novel AdS3 geometry with large superconformal symmetry.

Exotic branes and non-perturbative seven branes

We construct the effective action of certain exotic branes in the Type Ii theories which are not predicted by their space-time supersymmetry algebras. We analyze in detail the case of the NS-7B brane, S-dual to the D7-brane, and connected by T-duality to other exotic branes in Type IIA: the KK-6A brane and the KK-8A brane (obtained by reduction of the M-theory Kaluza-Klein monopole and M9-brane, respectively). The NS-7B brane carries charge with respect to the S-dual of the RR 8-form, which we identify as a non-local combination of the electric-magnetic duals of the axion and the dilaton. The study of its effective action agrees with previous results in the literature showing that it transforms as an SL(2,Z) triplet together with the D7-brane. We discuss why this brane is not predicted by the Type IIB space-time supersymmetry algebra. In particular we show that the modular transformation relating the D7 and NS-7B brane solutions can be undone by a simple coordinate transformation in the two-dimensional transverse space, equivalent to choosing a different region to parametrize the SL(2,Z) moduli space. We discuss a similar relation between the D6 and KK-6A branes and the D8 and KK-8A branes