REVIEW
Generalised T-Duality and Non-Geometric Backgrounds
High Energy Physics - Theory · Submitted 1 Dec 2005 · 30 references
Pith's verdict: The paper that opened the Q/R flux story; the derivations are clean, but the general both-twist backgrounds are proposed, not constructed, and the authors say so.
T0 · AI review
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Referee report
The paper
The paper claims
T-duality is extended to backgrounds where no circle is an isometry, producing spaces that depend on winding coordinates.
The reading
What carries the argument
The load-bearing device is the doubled geometry: a torus $T^d$ is promoted to a doubled torus with coordinates $y^i$ and dual coordinates $x_i$, and the T-duality group $O(d,d;Z)$ acts geometrically on the doubled torus even when it acts non-geometrically on $y$ alone. A duality-twisted reduction with monodromy $M$ becomes a bundle over a doubled base, and T-duality is a change of which coordinate is called spacetime. The second device is the scalar potential $W(K) = (1/12) K^{ad} K^{be} K^{cf} f_{abc} f_{def} - (1/4) K^{ad} L^{be} L^{cf} f_{abc} f_{def}$, fixed by matching the Scherk-Schwarz result of Kaloper and Myers and then extended by $O(d,d)$ covariance to arbitrary gaugings; its cubic term in the WZW case gives the determinant form of the Higgs field and the correct flat direction.
Extended reading notes
Core claim
The central claim is that there is a class of non-geometric string backgrounds with genuine dependence on the dual coordinates conjugate to winding number, sitting alongside ordinary flux compactifications and T-folds. T-folds are locally ordinary spacetimes glued by T-duality transition functions; the new backgrounds are stranger, since even locally they are not manifolds. The authors argue that a generalised T-duality acts on this wider class, taking a twisted-torus flux compactification or a T-fold to one of the new backgrounds, and that this is the missing third T-duality of $T^3$ with constant $H$-flux, where the base circle is not an isometry. The mechanism is a change of polarisation in a doubled formalism: the conformal field theory carries both momentum and winding labels, one chooses which coordinate to call spacetime, and the physics is claimed to be independent of that choice. They further construct the bosonic sector of the corresponding gauged supergravities in any dimension, with a universal scalar potential quadratic in the embedding tensor, and check it against the $SO(3)$ WZW model, where the potential reproduces the expected symmetry breaking to $SO(2)$ times $SO(2)$ with a single flat direction.
Load-bearing premise
The construction is classical throughout, and the claim that these dual-coordinate-dependent backgrounds are genuine string backgrounds rests on assuming that the doubled-formalism solutions lift to modular-invariant quantum theories away from the special moduli points where they reduce to known asymmetric orbifolds.
Editorial extensions
If this is right
- Mirror symmetry for Calabi-Yau manifolds with $T^3$ fibration and $H$-flux would have a concrete non-geometric mirror, obtained by T-dualising all fibre directions, as the Strominger-Yau-Zaslow picture suggests when flux is included.
- Gauged supergravities whose non-abelian gauge fields come from the antisymmetric tensor, rather than from isometries of the internal metric, acquire classical string liftings, removing an apparent obstruction to lifting a wide class of effective theories.
- The universal potential gives a complete nonlinear description of a class of WZW-model deformations, including the leading $1/k$ correction to the central charge, which is otherwise an $\alpha'$ effect invisible to supergravity.
- Every background reached by these generalised dualities inherits the quantum consistency of the background it came from, so T-duals of consistent T-folds are consistent even when no sigma-model metric can be written.
Reading between the lines
- If dual-coordinate dependence is real, momentum modes and winding modes probe different effective geometries of the same background, which suggests that any operational definition of the spacetime in these models must specify the probe, a point the paper raises but does not resolve.
- The construction predicts that the localised NS5-brane on a circle and the Kaluza-Klein monopole are related by a duality that produces dual-coordinate dependence in the monopole, matching the world-sheet instanton computations cited from Gregory-Harvey-Moore and Tong; a direct check of the full nonlinear map would be a sharp test.
- Because the doubled torus is a genuine manifold with an $SL(2d;Z)$ action, one could ask whether the doubled description admits a variational principle and a well-defined path integral of its own, which would make the polarisation-independence claim into a theorem rather than a bookkeeping device.
- Extending the same logic to U-duality would replace winding by brane wrapping, so the analogous exotic backgrounds would depend on coordinates conjugate to membrane and fivebrane charges; the paper flags this as future work, and it is where the classical treatment is most likely to fail first.
Original abstract
We undertake a systematic analysis of non-geometric backgrounds in string theory by seeking stringy liftings of a class of gauged supergravity theories. In addition to conventional flux compactifications and non-geometric T-folds with T-duality transition functions, we find a new class of non-geometric backgrounds with non-trivial dependence on the dual coordinates that are conjugate to the string winding number. We argue that T-duality acts in our class of theories, including those cases without isometries in which the conventional Buscher rules cannot be applied, and that these generalised T-dualities can take T-folds or flux compactifications on twisted tori to examples of the new non-geometric backgrounds. We show that the new class of non-geometric backgrounds and the generalised T-dualities arise naturally in string field theory, and are readily formulated in terms of a doubled geometry, related to generalised geometry. At special points in moduli space, some of the non-geometric constructions become equivalent to asymmetric orbifolds which are known to provide consistent string backgrounds. We construct the bosonic sector of the corresponding gauged supergravity theories and show that they have a universal form in any dimension, and in particular construct the scalar potential. We apply this to the supersymmetric WZW model, giving the complete non-linear structure for a class of WZW-model deformations.
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 undertake a systematic analysis of non-geometric backgrounds in string theory by seeking stringy liftings of a class of gauged supergravity theories. In addition to conventional flux compactifications and non-geometric T-folds with T-duality transition functions, we find a new class of non-geometric backgrounds with non-trivial dependence on the dual coordinates that are conjugate to the string winding number. We argue that T-duality acts in our class of theories, including those cases without isometries in which the conventional Buscher rules cannot be applied, and that these generalised T-dualities can take T-folds or flux compactifications on twisted tori to examples of the new non-geometric backgrounds. We show that the new class of non-geometric backgrounds and the generalised T-dualities arise naturally in string field theory, and are readily formulated in terms of a doubled geometry, related to generalised geometry. At special points in moduli space, some of the non-geometric constructions become equivalent to asymmetric orbifolds which are known to provide consistent string backgrounds. We construct the bosonic sector of the corresponding gauged supergravity theories and show that they have a universal form in any dimension, and in particular construct the scalar potential. We apply this to the supersymmetric WZW model, giving the complete non-linear structure for a class of WZW-model deformations.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We undertake a systematic analysis of non-geometric backgrounds in string theory by seeking stringy liftings of a class of gauged supergravity theories. | contribution 0.94 | 0.95 | 0.08 | asserted 0.89 |
| s1 | In addition to conventional flux compactifications and non-geometric T-folds with T-duality transition functions, we find a new class of non-geometric backgrounds with non-trivial dependence on the dual coordinates that are conjugate to the string winding number. | result 0.89 | 0.95 | 0.23 | asserted 1.00 |
| s2 | We argue that T-duality acts in our class of theories, including those cases without isometries in which the conventional Buscher rules cannot be applied, and that these generalised T-dualities can take T-folds or flux compactifications on twisted tori to examples of the new non-geometric backgrounds. | result 0.44 | 0.84 | 0.39 | asserted 0.74 |
| s3 | We show that the new class of non-geometric backgrounds and the generalised T-dualities arise naturally in string field theory, and are readily formulated in terms of a doubled geometry, related to generalised geometry. | result 0.64 | 0.92 | 0.17 | asserted 1.00 |
| s4 | At special points in moduli space, some of the non-geometric constructions become equivalent to asymmetric orbifolds which are known to provide consistent string backgrounds. | result 0.95 | 0.68 | 0.07 | asserted 0.76 |
| s5 | We construct the bosonic sector of the corresponding gauged supergravity theories and show that they have a universal form in any dimension, and in particular construct the scalar potential. | contribution 0.66 | 0.97 | 0.09 | asserted 1.00 |
| s6 | We apply this to the supersymmetric WZW model, giving the complete non-linear structure for a class of WZW-model deformations. | contribution 0.79 | 0.95 | 0.07 | asserted 1.00 |
What was examined, and what was not
- arXiv listing abstract v2
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References
How later papers used it
78 later papers cite it
1 later paper by other authors is listed below: 1 built on it. 2 more papers by the same authors are listed: 1 built on it and 1 used its method or tool.
Builds on it 2 of 3 papers with this label · 1 by the same authors
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Extended this paper's results and showed that all fluxes appearing in M-theory compactifications on manifolds with SU(3) structure that gauge isometries in the vector multiplet sector have a correspondent in heterotic compactifications with duality twists.
Heterotic type IIA duality with fluxes - towards the complete story (2010) · 0.91 · paraphrased: the licence does not allow quoting
By the same authors
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Extended the Buscher transformation to the case with dependence on both x and x, providing a generalisation of T-duality of the kind proposed in this paper.
Double Field Theory (2009) (same authors) · 0.84 · paraphrased: the licence does not allow quoting
Uses its method or tool 1 of 2 papers with this label · 1 by the same authors
By the same authors
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Used a generalised T-duality from this paper, which takes a background with dependence on x to an essentially doubled background whose fields depend on the coordinate of the T-dual circle.
Noncommutative gauge theories on D-branes in non-geometric backgrounds (2019) (same authors) · 0.98 · paraphrased: the licence does not allow quoting
How the literature uses it
72 arXiv papers cite this in 144 sentences
Papers citing it · 99 sentences without a confident label
Builds on it 3 papers
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In section [ref] we extended the results in [ref] and showed that all the fluxes which appear in M-theory compactifications on manifolds with $SU(3)$ structure and which gauge isometries in the vector multiplet sector have a correspondent in heterotic compactifications with duality twists as discussed in [ref] .
Heterotic type IIA duality with fluxes - towards the complete story · Conclusions · 0.91
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This example with $R$-flux arose from the replacement ([ref]) of $x$ with $x$ in the T-fold generalised metric ([ref]), so that it may be viewed as a $T^2$ fibration over the dual coordinate $x̃∼𝕏^1$ [ref] .
Non-geometric backgrounds, doubled geometry and generalised T-duality · R-Flux · 0.81
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The Buscher transformation of $$ was extended to the case with dependence on both $x$ and $x$, providing a generalisation of T-duality of the kind proposed in [ref] .
Double Field Theory · Spaces large and small · 0.84
Uses its method or tool 2 papers
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For such cases, we use a generalised T-duality [ref] which takes a background with dependence on $x$ to an essentially doubled background in which the fields depend on the coordinate $$ of the T-dual circle and so are problematic to interpret in conventional terms.
Noncommutative gauge theories on D-branes in non-geometric backgrounds · D-branes and doubled twisted torus geometry · 0.98
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For the three-dimensional backgrounds considered here there is no isometry, even locally, in the $x$-direction, so we cannot use the Buscher rules, even on a cover of the space; however, in section three we shall perform a non-isometric or `generalised duality' along the lines of that of [ref] and suggest another dual description of this background.
Flux compactifications, twisted tori and doubled geometry · T-duality and T-folds · 0.81
Compares with it 1 paper
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It will be argued that the $Q$-flux is akin to that found for the T-folds studied in [ref] where the monodromy around the $T^2$ cycles include a strict T-duality and mixes metric and $B$-field degrees of freedom.
N=4 Gauged Supergravity from Duality-Twist Compactifications of String Theory · Introduction · 0.93
Cites it as support 3 papers
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However, there is some evidence that there should be a generalisation of T-duality that applies to the case of a torus fibration where the torus action is not isometric [ref] .
Non-geometric backgrounds, doubled geometry and generalised T-duality · Introduction · 0.97
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Evidence for such a non-isometric T-duality was given in [ref] .
Flux compactifications, twisted tori and doubled geometry · Non-geometric backgrounds and gauged supergravity · 0.97
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Furthermore, there is evidence that the existence of an isometry, even locally, is not a requirement for T-duality to be possible [ref] .
N=4 Gauged Supergravity from Duality-Twist Compactifications of String Theory · Conclusion, Discussion and Future Directions · 0.99
Cites it as background 30 papers
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The doubled formalism [ref] was introduced to describe string backgrounds with a toroidal fibre in a manner which makes the T-duality action on the fibre into a manifest symmetry of a sigma model.
A Double Sigma Model for Double Field Theory · Relation to the doubled formalism · 0.97
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In order to rewrite the string sigma model in a way in which T-duality is manifest, Hull introduced the doubled formalism [ref] .
Connecting T-duality invariant theories · The doubled formalism · 0.97
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For non-isometric directions, there is a notion of generalised T-duality that can be applied [ref] .
Noncommutative gauge theories on D-branes in non-geometric backgrounds · Introduction and summary · 0.81
Discussion
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