REVIEW
G-structures and Flavouring non-Abelian T-duality
High Energy Physics - Theory · Submitted 30 May 2013 · 36 references
Pith's verdict: A solid, honest paper that delivers on T^{1,1} and adds a genuinely new flavoured IIA solution, though the general SU(3)→SU(2) statement is asserted by analogy rather than proved.
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Referee report
The paper
The paper claims
Non-Abelian T-duality along an SU(2) isometry converts a supersymmetric background with SU(3)-structure into one with SU(2)-structure, and the paper gives the explicit rule for how the underlying pure spinors transform.
The reading
What carries the argument
The load-bearing device is the pair of pure-spinor transformation rules inherited from the spinor rotation $Omega$ that relates the left- and right-moving frames of the dual $\sigma$ model. Because $Omega$ is built from the same data that defines the original SU(3)-structure, the T-dual pure spinors can be written directly in terms of the original ones, and the resulting objects are of SU(2) type rather than SU(3) type. The second device is a compensating vielbein rotation, with parameters $zeta_1, zeta_2, zeta_3$ built from the T-dual coordinates, that brings the dual Killing spinor into a form as simple as the Abelian case; in that basis the projections on the original spinor are untouched while the second spinor obeys flipped projections, which is exactly the statement that the two spinors are nowhere parallel. The third device is the calibration polyform $Psi_{cal} = -8 e^{3A-Phi} mathrm{Im}Psi_- wedge e^B$, which converts the SU(2)-structure into a practical test of which D-branes can wrap which cycles.
Extended reading notes
Core claim
The central claim is that non-Abelian T-duality along an SU(2) group is type-changing for the internal geometry: SU(3)-structure goes in, SU(2)-structure comes out. The authors motivate this by an Abelian analogy — dualising a pair of directions that the complex structure pairs leaves the structure alone, while dualising directions it does not pair breaks it — and then make it precise with the transformation rules $/Psi^{SU(2)}_+ = i /Psi^{SU(3)}_- Omega^{-1}$ and $/Psi^{SU(2)}_- = /Psi^{SU(3)}_+ Omega^{-1}$, where $Omega$ is the spinor rotation induced by the duality. For the T-dual of $AdS_5 imes T^{1,1}$ they exhibit the two internal spinors explicitly, show that after a suitable rotation of the vielbein the second spinor takes the simple form $ildeeta_{2-} = -i ildetilde{gamma}_r eta_+$, and read off the SU(2)-structure forms $v+iw = -ilde{e}_3 + i ilde{e}_r$, $j = ilde{e}_{hetaphi} + ilde{e}_{21}$, $omega = (ilde{e}_2 + i ilde{e}_1) wedge (ilde{e}_heta + i ilde{e}_phi)$. They extend the same analysis to the flavoured Klebanov–Witten background with smeared D7 sources, obtaining a type IIA solution supported by D6 and D8 sources whose potentials and calibrations are expressed entirely in the SU(2)-structure data, and they check that the DBI and Wess–Zumino actions cancel for calibrated cycles.
Load-bearing premise
The general claim rests on the assumption that the pure-spinor transformation rule commutes with the twisted differential $d_H$, which the paper states it has not verified in detail, and on the analogous unproved generality of the Ramond–Ramond potential transformation rule.
Editorial extensions
If this is right
- Any N=1 background with an SU(2) isometry can be dualised and then analysed with SU(2)-structure technology, rather than requiring a case-by-case Killing-spinor computation.
- The T-dual of a flavoured background carries explicit D6 and D8 sources, and the paper shows how the smearing forms transform in parallel with the Ramond–Ramond fields, giving a general recipe for dualising brane sources.
- Because the source content depends on the choice of $B$-field gauge, the split between explicit D6 and D4 charge is gauge-dependent, while the total Maxwell charge and the equations of motion are invariant.
- The calibrated cycles found in the dual geometry — spacetime-filling D4, D6 and D8 branes wrapping specific submanifolds — give candidate domain walls and defects in whatever field theory the background duals.
- The same procedure should apply to the wider family of N=1 backgrounds previously generated by non-Abelian T-duality, and to more general toric Calabi–Yau geometries.
Reading between the lines
- If the SU(3)-to-SU(2) map is generic, it suggests a rough counting statement: each SU(2) isometry dualised costs one complex structure pairing, so backgrounds with larger dualised isometry groups should land further down the G-structure hierarchy.
- The gauge-dependence of the D6/D4 split is reminiscent of the Myers dielectric effect run backwards; a reader could ask whether the same redistribution of charge appears when the duality is applied to a single localised (unsmeared) flavour brane rather than a smeared stack.
- The paper leaves the periodicity of the new coordinates $x_1, x_2$ open; until that is fixed, the flux quantisation and hence the field-theory rank assignments of the dual background remain ambiguous.
- Since the transformation rule is asserted by analogy with the Abelian case rather than proved, an independent check would be to verify that the Clifford multiplication commutes with $d_H$ on a background with non-trivial $H$, which the paper does not do.
Original abstract
We examine non-Abelian T-duality on backgrounds preserving N=1 supersymmetry. We show how backgrounds with SU(3)-structure are mapped to backgrounds with SU(2)-structure. We provide the transformation rules for the corresponding pure spinors. We use these techniques to construct new flavoured solutions of type IIA supergravity.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We examine non-Abelian T-duality on backgrounds preserving N=1 supersymmetry. We show how backgrounds with SU(3)-structure are mapped to backgrounds with SU(2)-structure. We provide the transformation rules for the corresponding pure spinors. We use these techniques to construct new flavoured solutions of type IIA supergravity.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We examine non-Abelian T-duality on backgrounds preserving N=1 supersymmetry. | contribution 0.74 | 0.90 | 0.07 | asserted 0.87 |
| s1 | We show how backgrounds with SU(3)-structure are mapped to backgrounds with SU(2)-structure. | result 0.72 | 0.93 | 0.29 | asserted 1.00 |
| s2 | We provide the transformation rules for the corresponding pure spinors. | contribution 0.71 | 0.94 | 0.10 | asserted 1.00 |
| s3 | We use these techniques to construct new flavoured solutions of type IIA supergravity. | contribution 0.77 | 0.95 | 0.48 | asserted 1.00 |
What was examined, and what was not
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- P abstract
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References
How the literature uses it
33 arXiv papers cite this in 63 sentences
Papers citing it · 39 sentences without a confident label
Uses its method or tool 2 papers
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Fortunately we can exploit a map for the $SU(2)$ transformation of the pure spinors that was proposed in [ref] Ψ̂_±= Ψ_∓ Ω^-1_SU(2), where in general, in the frame of eq ([ref]) Ω_SU(2)= 1/√(1+ζ_a^2)Γ^(10)(-Γ_456 +∑_a=1^3ζ_aΓ^a+3), for $ζ_a$ defined as in [ref] , which for our parametrisation of ABJM specifically is ζ_1= 4/L^2 cosζsin^2ζy_1 cosξ, ζ_2= 4/L^2 cosζsin^2ζy_1 sinξ, ζ_3= 4 /L^2 sin^2ζy_2.
A $\mathcal{N}=2$ Supersymmetric $AdS_4$ Solution in M-theory with Purely Magnetic Flux · A $U(1)$ of $SU(2)$-structures in the Non-Abelian T-dual · 0.99
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[ref] via the map given in [ref] Ψ_±= Ψ_∓Ω^-1.
Holographic Flows in non-Abelian T-dual Geometries · Type IIA/M-theory non-Abelian T-dual backgrounds of the flow ansatz · 0.93
Compares with it 5 papers
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* The non-conformality of the geometry is enabled by a non-zero Romans' mass. * Whilst the UV geometries proposed in [ref] are characterized by static $SU(2)$ structure [ref] the full IR complete geometry of this paper has dynamic $SU(2)$ structure. * The transition to dynamic $SU(2)$ structure gives a geometric realization of confinement and permits supersymmetric D2 branes that act as domain walls in the IR.
Dualising the Baryonic Branch: Dynamic SU(2) and confining backgrounds in IIA · Conclusions and Future Directions · 0.82
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In the UV, this structure flows to the orthogonal $SU(2)$ structure of the KW solution presented in [ref] .
Non-Abelian T-Dualizing the Resolved Conifold with Regular and Fractional D3-Branes · Comments on the G-structure of the solution · 0.89
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The latter could then be interpreted as the field of$$̱-supergravity, providing a new understanding of a dynamical SU(2) structure.[The non-abelian T-duality transformation described in [ref] looks analogous to [ref]; it would be interesting to compare the two, given our discussion and the result of [ref] .] Let us reformulate this idea more precisely. ]
Supersymmetry with non-geometric fluxes, or a $\beta$-twist in Generalized Geometry and Dirac operator · $$̱-twist and intermediate or dynamical SU(2) structure solutions$ · 0.80
Cites it as support 1 paper
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Although we have not provided a proof that one implies the other there is mounting evidence that this is indeed the case [ref] , and a proof for the situation for $SU(2)⊂SO(4)$ [ref] .
A new AdS_4/CFT_3 Dual with Extended SUSY and a Spectral Flow · Conclusions · 1.00
Cites it as background 12 papers
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The T-dual solution that we consider here has been studied in detail in [ref] .
The non-Abelian T-dual of Klebanov-Witten Background and its Penrose Limits · The Non-Abelian T-dual of the Klebanov-Witten Background · 0.86
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Despite these open problems, recently we have witnessed a small resurgence in interest in non-Abelian T-duality, spurred on by the extension of non-Abelian T-duality to incorporate RR fields [ref] .[See also [ref] for the role the Fourier-Mukai transform plays in the transformation of the RR fields.] Provided one is careful about the R symmetry, it is possible to generate supersymmetry preserving solutions of relevance in the context of gauge/gravity duality [ref] as well as to study the implications for G-structures [ref] .
Hints of 5d Fixed Point Theories from Non-Abelian T-duality · Introduction · 0.94
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This problem is addressed in various papers, notably in [ref] .
Pin(d,d) covariance of pure spinor equations for supersymmetric vacua and Non-Abelian T-duality · Introduction · 0.92
What it cites · 52 sentences without a confident label
Builds on 3 papers
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In section 4 we look at examples of the T-dual of the un-flavoured Klebanov-Witten model studied in [ref] and explicitly construct its $SU(2)$-structure.
On Non-Abelian T-Duality and new N=1 backgrounds · Introduction · 0.80
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In section 4 we look at examples of the T-dual of the un-flavoured Klebanov-Witten model studied in [ref] and explicitly construct its $SU(2)$-structure.
Non-Abelian T-duality and the AdS/CFT correspondence:new N=1 backgrounds · Introduction · 0.80
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We will then consider the background obtained by adding fundamental fields (quarks) to the Klebanov-Witten field theory [ref] (conversely, we will consider the addition of source-branes to the Klebanov-Witten background).
Unquenched Flavors in the Klebanov-Witten Model · G-structures and their transformations · 0.86
Uses the method or tool of 1 paper
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To compactly display the results it is convenient to perform a supplementary rotation as detailed in equation (3.21) of [ref] .
Non-Abelian T-duality and the AdS/CFT correspondence:new N=1 backgrounds · The T-dual · 0.99
Compares with 1 paper
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For instance applying an $SU(2)$ non-Abelian T-duality to the internal space of the Klebanov–Witten background ($AdS^5 ×T^1,1$) results in a solution of type IIA which retains the $AdS_5$ factor and has a lift to M-theory which corresponds to the geometries obtained in [ref] from wrapping M5 branes on an $S^2$.
Four-Dimensional SCFTs from M5-Branes · Introduction · 0.87
Cites as support 1 paper
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If on the other hand this vanishes only for some projected subset of Killing spinors then we expect only a corresponding projected amount of supersymmetry to be preserved in the T-dual.[In [ref] this was confirmed to be true in general for a large class of backgrounds.] In this paper we consider the case of $N= 1$ supersymmetry which is invariant under the above action of $G$ so that the non-Abelian duality should preserve supersymmetry.
Non-Abelian T-duality and consistent truncations in type-II supergravity · Non-Abelian T-duality · 0.97
Cites as background 14 papers
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The recent work of Itsios et al. [ref] considered the application of this duality transformation in IIB supergravity backgrounds preserving $N=1$ supersymmetry.
Non-Abelian T-duality and the AdS/CFT correspondence:new N=1 backgrounds · Introduction · 0.91
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The recent work of Itsios et al. [ref] considered the application of this duality transformation in IIB supergravity backgrounds preserving $N=1$ supersymmetry.
On Non-Abelian T-Duality and new N=1 backgrounds · Introduction · 0.91
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Although the idea of generalising T-duality to non-Abelian isometry groups has rather old roots [ref] , it is only recently that it has been studied as full solution-generating symmetry of supergravity [ref] .
Non-abelian T-duality, Ramond Fields and Coset Geometries · Introduction · 1.00
Discussion
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