| 1. |
- 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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| 2. |
- Gran, Ulf, 1973, et al.
(författare)
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Classification, geometry and applications of supersymmetric backgrounds
- 2019
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573. ; 11:5, s. 1-87
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Forskningsöversikt (refereegranskat)abstract
- We review the remarkable progress that has been made the last 15 years towards the classification of supersymmetric solutions with emphasis on the description of the bilinears and spinorial geometry methods. We describe in detail the geometry of backgrounds of key supergravity theories, which have applications in the context of black holes, string theory, M-theory and the AdS/CFT correspondence unveiling a plethora of existence and uniqueness theorems. Some other aspects of supersymmetric solutions like the Killing superalgebras and the homogeneity theorem are also presented, and the non-existence theorem for certain smooth supergravity flux compactifications is outlined. Amongst the applications described is the proof of the emergence of conformal symmetry near black hole horizons and the classification of warped AdS backgrounds that preserve more than 16 supersymmetries.
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| 3. |
- Gran, Ulf, 1973, et al.
(författare)
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Classification of IIB backgrounds with 28 supersymmetries
- 2009
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We show that all IIB backgrounds with strictly 28 supersymmetries are locally isometric to the plane wave solution of arXiv:hep-th/0206195. Moreover, we demonstrate that all solutions with more than 26 supersymmetries and only 5-form flux are maximally supersymmetric. The N=28 plane wave solution is a superposition of the maximally supersymmetric IIB plane wave with a heterotic string solution. We investigate the propagation of strings in this background, find the spectrum and give the string light-cone Hamiltonian.
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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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Geometry of all supersymmetric four-dimensional N=1 supergravity backgrounds
- 2008
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 06:6, s. 102-
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Tidskriftsartikel (refereegranskat)abstract
- We solve the Killing spinor equations of ${\cal N}=1$ supergravity, with four supercharges, coupled to any number of vector and scalar multiplets in all cases. We find that backgrounds with N=1 supersymmetry admit a null, integrable, Killing vector field. There are two classes of N=2 backgrounds. The spacetime in the first class admits a parallel null vector field and so it is a pp-wave. The spacetime of the other class admits three Killing vector fields, and a vector field that commutes with the three Killing directions. These backgrounds are of cohomogeneity one with homogenous sections either $\bR^{2,1}$ or $AdS_3$ and have an interpretation as domain walls. The N=3 backgrounds are locally maximally supersymmetric. There are N=3 backgrounds which arise as discrete identifications of maximally supersymmetric ones. The maximally supersymmetric backgrounds are locally isometric to either $\bR^{3,1}$ or $AdS_4$.
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| 6. |
- Gran, Ulf, 1973, et al.
(författare)
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IIB backgrounds with five-form flux
- 2008
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Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213. ; 798:1-2, s. 36-71
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Tidskriftsartikel (refereegranskat)abstract
- We investigate all N=2 supersymmetric IIB supergravity backgrounds with non-vanishing five-form flux. The Killing spinors have stability subgroups $Spin(7)\ltimes\bR^8$, $SU(4)\ltimes\bR^8$ and $G_2$. In the $SU(4)\ltimes\bR^8$ case, two different types of geometry arise depending on whether the Killing spinors are generic or pure. In both cases, the backgrounds admit a null Killing vector field which leaves invariant the $SU(4)\ltimes \bR^8$ structure, and an almost complex structure in the directions transverse to the lightcone. In the generic case, the twist of the vector field is trivial but the almost complex structure is non-integrable, while in the pure case the twist is non-trivial but the almost complex structure is integrable and associated with relatively balanced Hermitian structure. The $G_2$ backgrounds admit a time-like Killing vector field and two spacelike closed one-forms, and the seven directions transverse to these admit a co-symplectic $G_2$ structure. The $Spin(7)\ltimes\bR^8$ backgrounds are pp-waves propagating in an eight-dimensional manifold with holonomy $Spin(7)$. In addition we show that all the supersymmetric solutions of simple five-dimensional supergravity with a time-like Killing vector field, which include the $AdS_5$ black holes, lift to $SU(4)\ltimes\bR^8$ pure Killing spinor IIB backgrounds. We also show that the LLM solution is associated with a co-symplectic co-homogeneity one $G_2$ manifold which has principal orbit $S^3\times S^3$.
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| 7. |
- Gran, Ulf, 1973, et al.
(författare)
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IIB solutions with N>28 Killing spinors are maximally supersymmetric
- 2007
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2007:12, s. 070-
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Tidskriftsartikel (refereegranskat)abstract
- We show that all IIB supergravity backgrounds which admit more than 28 Killing spinors are maximally supersymmetric. In particular, we find that for all N>28 backgrounds the supercovariant curvature vanishes, and that the quotients of maximally supersymmetric backgrounds either preserve all 32 or N
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| 8. |
- 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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| 9. |
- 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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| 10. |
- Gran, Ulf, 1973, et al.
(författare)
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The Classification of Highly Supersymmetric Supergravity Solutions
- 2009
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Ingår i: AIP Conf. Proc.: Proceedings of the Special Metrics and Supersymmetry conference at Universidad del Pais Vasco, May 2008.. ; 1093, s. 70-91
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Konferensbidrag (refereegranskat)abstract
- The spinorial geometry method is an effective method for constructing systematic classifications of supersymmetric supergravity solutions. Recent work on analysing highly supersymmetric solutions in type IIB supergravity using this method is reviewed [arXiv:hep-th/0606049, arXiv:0710.1829]. It is shown that all supersymmetric solutions of IIB supergravity with more than 28 Killing spinors are locally maximally supersymmetric.
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