| 1. |
- Gran, Ulf, 1973, et al.
(författare)
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IIB horizons
- 2013
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 30:20
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Tidskriftsartikel (refereegranskat)abstract
- We solve the Killing spinor equations for all near-horizon IIB geometries which preserve at least one supersymmetry. We show that generic horizon sections are eight-dimensional almost Hermitian spin(c) manifolds. Special cases include horizon sections with a Spin(7) structure and those for which the Killing spinor is pure. We also explain how the common sector horizons and the horizons with only 5-form flux are included in our general analysis. We investigate several special cases mainly focusing on the horizons with constant scalars admitting a pure Killing spinor and find that some of these exhibit a generalization of the 2-SCYT condition that arises in the horizons with 5-form fluxes only. We use this to construct new examples of near-horizon geometries with both 3-form and 5-form fluxes.
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| 2. |
- Gran, Ulf, 1973, et al.
(författare)
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Invariant Killing spinors in 11D and type II supergravities
- 2009
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 26:15
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Tidskriftsartikel (refereegranskat)abstract
- We present all isotropy groups and associated $\Sigma$ groups, up to discrete identifications of the component connected to the identity, of spinors of eleven-dimensional and type II supergravities. The $\Sigma$ groups are products of a Spin group and an R-symmetry group of a suitable lower dimensional supergravity theory. Using the case of SU(4)-invariant spinors as a paradigm, we demonstrate that the $\Sigma$ groups, and so the R-symmetry groups of lower-dimensional supergravity theories arising from compactifications, have disconnected components. These lead to discrete symmetry groups reminiscent of R-parity. We examine the role of disconnected components of the $\Sigma$ groups in the choice of Killing spinor representatives and in the context of compactifications.
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| 3. |
- Gran, Ulf, 1973, et al.
(författare)
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AdS backgrounds from black hole horizons
- 2013
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 30:5, s. Art. no. 055014-
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Tidskriftsartikel (refereegranskat)abstract
- We utilize the classification of IIB horizons with 5-form flux to present a unified description for the geometry of AdS(n), n = 3, 5, 7 solutions. In particular, we show that all such backgrounds can be constructed from eight-dimensional 2-strong Calabi-Yau geometries with torsion which admit some additional isometries. We explore the geometry of AdS(3) and AdS(5) solutions but we do not find AdS(7) solutions.
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| 4. |
- Gran, Ulf, 1973, et al.
(författare)
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Dynamical symmetry enhancement near massive IIA horizons
- 2015
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 32:23, s. Art. Nr. 235004-
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Tidskriftsartikel (refereegranskat)abstract
- We prove that Killing horizons in massive IIA supergravity preserve an even number of supersymmetries, and that their symmetry algebra contains an ??(2,R) subalgebra, confirming the conjecture of [5]. We also prove a new class of Lichnerowicz type theorems for connections of the spin bundle whose holonomy is contained in a general linear group.
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| 5. |
- Gran, Ulf, 1973, et al.
(författare)
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All superalgebras for warped AdS2 and black hole near horizon geometries
- 2019
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 36:23
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Tidskriftsartikel (refereegranskat)abstract
- We identify all symmetry superalgebras ? of near horizon geometries of black holes with a Killing horizon, assuming the solution is smooth and that the spatial cross section of the event horizon is compact without boundary. This includes all warped AdS2 backgrounds with the most general allowed fluxes in 10- and 11-dimensional supergravities. If the index of a particular Dirac operator vanishes, we find that the even symmetry subalgebra decomposes as ?0=??(2,ℝ)⊕?0, where ?0/? is the Lie algebra of a group that acts transitively and effectively on spheres, and ? is the center of ?. If the Dirac operator index does not vanish, then the symmetry superalgebra is nilpotent with one even generator. We also demonstrate that there are no near horizon geometries, and also therefore no warped AdS2 backgrounds, in 10- and 11-dimensions that preserve more than 16 supersymmetries.
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| 6. |
- Gran, Ulf, 1973, et al.
(författare)
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On supersymmetric anti-de Sitter, de Sitter and Minkowski flux backgrounds
- 2018
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Ingår i: Classical and Quantum Gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 35:6
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Tidskriftsartikel (refereegranskat)abstract
- We test the robustness of the conditions required for the existence of (supersymmetric) warped flux anti-de Sitter, de Sitter, and Minkowski backgrounds in supergravity theories using as examples suitable foliations of anti-de Sitter spaces. We find that there are supersymmetric de Sitter solutions in supergravity theories including maximally supersymmetric ones in 10- and 11-dimensional supergravities. Moreover, warped flux Minkowski backgrounds can admit Killing spinors which are not Killing on the Minkowski subspace and therefore cannot be put in a factorized form.
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