arXiv subjects

Ilya Bakhmatov

Publications and source records attributed to Ilya Bakhmatov.

18 recordsLinked to original sources

arXiv2023

Non-abelian fermionic T-duality in supergravity

Field transformation rules of the standard fermionic T-duality require fermionic isometries to anticommute, which leads to complexification of the Killing spinors and results in complex valued dual backgrounds. We generalize the field transformations to the setting with non-anticommuting fermionic isometries and show that the resulting backgrounds are solutions of double field theory. Explicit examples of non-abelian fermionic T-dualities that produce real backgrounds are given. Some of our examples can be bosonic T-dualized into usual supergravity solutions, while the others are genuinely non-geometric. Comparison with alternative treatment based on sigma models on supercosets shows consistency.

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arXiv2022

Fermionic T-duality of DFT

We provide a complete proof that non-abelian fermionic T-duality along a non-anticommuting Killing spinor always generates a solution to double field theory equations. Examples of non-abelian fermionic T-dualities of string backgrounds with non-vanishing b-field are investigated.

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arXiv2022

Generalized 11D supergravity equations from tri-vector deformations

In arXiv:2203.03372 we presented a modification of 11-dimensional supergravity field equations which upon dimensional reduction yields generalized supergravity equations in 10-dimensions. In this paper we provide full technical details of that result which is based on SL(5) exceptional field theory. The equations are obtained by making a non-unimodular tri-vector Yang-Baxter deformation which breaks the initial GL(11) symmetry down to GL(7)xGL(4). We also give some non-trivial solutions to these equations.

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arXiv2022

Generalizing eleven-dimensional supergravity

We develop a procedure to reproduce the ten-dimensional generalized supergravity equations from T-duality covariant equations, that facilitates generalization to U-duality covariant formulations of eleven-dimensional supergravity. The latter leads to a modification of the eleven-dimensional supergravity equations with terms that contain a rank-2 tensor field $J^{mn}$ which is the eleven-dimensional analog of the non-unimodularity Killing vector $I^m$ in ten dimensions.

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arXiv2020

Non-abelian tri-vector deformations in d=11 supergravity

A truncation of the SL(5) Exceptional Field Theory that allows to describe spacetimes of the form $M_4 \times M_7$ with the 4-form flux on $M_4$ is constructed. The resulting theory is used to test the recently proposed tri-vector generalisation of Yang-Baxter deformations applied to the AdS${}_4 \times \mathbb{S}^7$ solution in $d=11$ supergravity. We present two new supergravity solutions corresponding to non-abelian non-unimodular tri-vector deformations of AdS${}_4 \times \mathbb{S}^7$.

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arXiv2019

Tri-vector deformations in $d=11$ supergravity

We construct a $d=11$ supergravity analogue of the open-closed string map in the context of SL(5) Exceptional Field Theory (ExFT). The deformation parameter tri-vector $Ω$ generalizes the non-commutativity bi-vector parameter $Θ$ of the open string. When applied to solutions in $d=11$, this map provides an economical way of performing TsT deformations, and may be used to recover $d=10$ Yang-Baxter deformations after dimensional reduction. We present a generalization of the Classical Yang-Baxter Equation (CYBE) for rank 3 objects, which emerges from $d=11$ supergravity and the SL(5) ExFT. This equation is shown to reduce to the $d=10$ CYBE upon dimensional reduction.

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arXiv2019

Classical Yang-Baxter equation from beta-supergravity

Yang-Baxter deformations of superstring sigma-models have recently inspired a supergravity solution generating technique. Using the open/closed string map and a Killing bi-vector as a deformation parameter, new solutions can be built, such that the (generalised) supergravity field equations were conjectured to always reduce to the classical Yang-Baxter equation (CYBE). In this work we provide a proof of this conjecture, using a systematic approach based on the so-called $β$-supergravity, which is a dynamical theory for the field $β^{mn}$ instead of the NSNS 2-form $b_{mn}$.

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arXiv2018

Exotic branes in Exceptional Field Theory: the SL(5) duality group

We study how exotic branes, i.e. branes whose tensions are proportional to $g_s^{-α}$, with $α>2$, are realised in Exceptional Field Theory (EFT). The generalised torsion of the Weitzenböck connection of the $\operatorname{SL}(5)$ EFT which, in the language of gauged supergravity describes the embedding tensor, is shown to classify the exotic branes whose magnetic fluxes can fit into four internal dimensions. By analysing the weight diagrams of the corresponding representations of $\operatorname{SL}(5)$ we determine the U-duality orbits relating geometric and non-geometric fluxes. As a further application of the formalism we consider the Kaluza-Klein monopole of 11D supergravity and rotate it into the exotic $6^{(3,1)}$-brane.

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arXiv2018

Conformal Twists, Yang-Baxter $σ$-models & Holographic Noncommutativity

Expanding upon earlier results [arXiv:1702.02861], we present a compendium of $σ$-models associated with integrable deformations of AdS$_5$ generated by solutions to homogenous classical Yang-Baxter equation. Each example we study from four viewpoints: conformal (Drinfeld) twists, closed string gravity backgrounds, open string parameters and proposed dual noncommutative (NC) gauge theory. Irrespective of whether the deformed background is a solution to supergravity or generalized supergravity, we show that the open string metric associated with each gravity background is undeformed AdS$_5$ with constant open string coupling and the NC structure $Θ$ is directly related to the conformal twist. One novel feature is that $Θ$ exhibits "holographic noncommutativity": while it may exhibit non-trivial dependence on the holographic direction, its value everywhere in the bulk is uniquely determined by its value at the boundary, thus facilitating introduction of a dual NC gauge theory. We show that the divergence of the NC structure $Θ$ is directly related to the unimodularity of the twist. We discuss the implementation of an outer automorphism of the conformal algebra as a coordinate transformation in the AdS bulk and discuss its implications for Yang-Baxter $σ$-models and self-T-duality based on fermionic T-duality. Finally, we comment on implications of our results for the integrability of associated open strings and planar integrability of dual NC gauge theories.

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arXiv2017

Yang-Baxter $σ$-models, conformal twists, and noncommutative Yang-Mills theory

The Yang-Baxter $σ$-model is a systematic way to generate integrable deformations of AdS$_5\times$S$^5$. We recast the deformations as seen by open strings, where the metric is undeformed AdS$_5\times$S$^5$ with constant string coupling, and all information about the deformation is encoded in the noncommutative (NC) parameter $Θ$. We identify the deformations of AdS$_5$ as twists of the conformal algebra, thus explaining the noncommutativity. We show that the unimodularity conditon on $r$-matrices for supergravity solutions translates into $Θ$ being divergence-free. Integrability of the $σ$-model for unimodular $r$-matrices implies the existence and planar integrability of the dual NC gauge theory.

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arXiv2016

Non-geometric branes are DFT monopoles

The double field theory monopole solution by Berman and Rudolph is shown to reproduce non-geometric backgrounds with non-vanishing Q- and R-flux upon an appropriate choice of physical and dual coordinates. The obtained backgrounds depend non-trivially on dual coordinates and have only trivial monodromies. Upon smearing the solutions along the dual coordinates one reproduces the known $5^2_2$ solution for the Q-brane and co-dimension 1 solution for the R-brane. The T-duality invariant magnetic charge is explicitly calculated for all these backgrounds and is found to be equal to the magnetic charge of (unsmeared) NS5-brane.

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arXiv2015

Fermionic T-duality in massive type IIA supergravity on AdS_{10-k} x M_k

Fermionic T-duality transformation is studied for the N=1 supersymmetric solutions of massive type IIA supergravity with the metric AdS_{10-k} x M_k for k=3 and 5. We derive the Killing spinors of these backgrounds and use them as an input for the fermionic T-duality transformation. The resulting dual solutions form a large family of supersymmetric deformations of the original solutions by complex valued RR fluxes. We observe that the Romans mass parameter does not change under fermionic T-duaity, and prove its invariance in the k=3 case.

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arXiv2015

Exceptional field theory: $SO(5,5)$

We construct Exceptional Field Theory for the group $SO(5,5)$ based on the extended (6+16)-dimensional spacetime, which after reduction gives the maximal $D=6$ supergravity. We present both a true action and a duality-invariant pseudo-action formulations. All the fields of the theory depend on the complete extended spacetime. The U-duality group $SO(5,5)$ is made a geometric symmetry of the theory by virtue of introducing the generalised Lie derivative that incorporates a local duality transformation. Tensor hierarchy appears as a natural consequence of the algebra of generalised Lie derivatives that are viewed as gauge transformations. Upon truncating different subsets of the extra coordinates, maximal supergravities in $D=11$ and $D=10$ (type IIB) can be recovered from this theory.

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arXiv2013

Pure Spinor b-ghost in a Super-Maxwell Background

In the pure spinor formalism for the superstring, the b-ghost is a composite operator satisfying {Q,b}=T where Q is the pure spinor BRST operator and T is the holomorphic stress tensor. The b-ghost is holomorphic in a flat target-space background, but it is not holomorphic in a generic curved target-space background and instead satisfies $\bar\partial b$ = [Q, Ω] for some Ω. In this paper, Ω is explicitly constructed for the case of an open superstring in a super-Maxwell background.

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arXiv2012

Fermionic T-duality and U-duality in type II supergravity

This thesis deals with the two duality symmetries of N=2 D=10 supergravity theories that are descendant from the full superstring theory: fermionic T-duality and U-duality. The fermionic T-duality transformation is applied to the D-brane and pp-wave solutions of type IIB supergravity. New supersymmetric solutions of complexified supergravity are generated. We show that the pp-wave yields a purely imaginary background after two dualities, undergoes a geometric transformation after four dualities, and is self-dual after eight dualities. Next we apply six bosonic and six fermionic T-dualities to the AdS_4 x CP^3 background of type IIA supergravity, which is relevant to the current research in the amplitude physics. This helps to elucidate the potential obstacles in establishing the self-duality, and quite independently from that shows us that fermionic T-dualities may be degenerate under some circumstances. Finally, we make a step towards constructing a manifestly U-duality covariant action for D=10 supergravities by deriving the generalized metric for a D1-brane. This is a single structure that treats brane wrapping coordinates on the same footing as spacetime coordinates. It turns out that the generalized metric of a D-string results from that of the fundamental string if one replaces the spacetime metric with the open string metric. We also find an antisymmetric contribution to the generalized metric that can be interpreted as a noncommutativity parameter.

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arXiv2011

Fermionic T-duality in the pp-wave limit

AdS5 X S5 and its pp-wave limit are self-dual under transformations involving eight fermionic T-dualities, a property which accounts for symmetries seen in scattering amplitudes in N=4 super-Yang-Mills. Despite strong evidence for similar symmetries in the amplitudes of three-dimensional N=6 ABJM theory, a corresponding self-duality in the dual geometry AdS4 X CP3 currently eludes us. Here, working with the type IIA pp-wave limit of AdS4 X CP3 preserving twenty four supercharges, we show that the pp-wave is self-dual with respect to eight commuting fermionic T-dualities and not the six expected. In addition, we show the same symmetry can be found in a superposition pp-wave and a generic pp-wave with twenty and sixteen unbroken supersymmetries respectively, strongly suggesting that self-duality under fermionic T-duality may be a symmetry of all pp-waves.

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arXiv2010

On AdS_4 x CP^3 T-duality

We give a supergravity treatment of the set of bosonic and fermionic T-dualities in the AdS_4 x CP^3 background. We consider T-dualities along three flat AdS_4 directions, three complexified isometries of CP^3, and six fermionic T-dualities. Concentrating on the transformation of the dilaton, we give description of the singularity that arises in the transformation.

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arXiv2010

Exploring Fermionic T-duality

The fermionic T-duality transformation developed by Berkovits and Maldacena is applied to D-brane and the pp-wave solutions of type IIB supergravity. The pp-wave is found to be self-dual under the combination of dualities. We explore the consequences of applying the transformation and discuss various properties of the new transformed solutions.

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