• Euclidean supergravity and multi-centered solutions 

  Sabra, Wafic A. (Elsevier B.V., 2017)

  In ungauged supergravity theories, the no-force condition for BPS states implies the existence of stable static multi-centered solutions. The first solutions to Einstein–Maxwell theory with a positive cosmological constant ...
• The case of HD 106906 debris disc: a binary's revenge 

  Farhat, Mohammad A.; Sefilian, Antranik A.; Touma, Jihad R. (Oxford University Press, 2023)

  Debris disc architecture presents [exo-]planetary scientists with precious clues for processes of planet formation and evolution, including constraints on planetary mass perturbers. This is particularly true of the disc ...
• Special geometry and space–time signature 

  Sabra, Wafic A. (Elsevier B.V., 2017)

  We construct N=2 four and five-dimensional supergravity theories coupled to vector multiplets in various space–time signatures (t,s), where t and s refer, respectively, to the number of time and spatial dimensions. The ...
• The vertical structure of debris discs and the impact of gas 

  Olofsson, Johan; Thébault, Philippe; Kral, Quentin; Bayo, Amelia; Boccaletti, Anthony; Godoy, Nicolas; Henning, Th; van Holstein, Rob G.; Maucó, Karina; Milli, Julien; Montesinos, Matías A.; Rein, Hanno; Sefilian, Antranik A. (Oxford University Press, 2022)

  The vertical structure of debris discs provides clues about their dynamical evolution and the collision rate of the unseen planetesimals. Thanks to the ever-increasing angular resolution of contemporary instruments and ...
• A note on the Hyper-CR equation, and gauged N = 2 supergravity 

  Dunajski, Maciej; Gutowski, Jan B.; Sabra, Wafic A. (Elsevier B.V., 2018)

  We construct a new class of solutions to the dispersionless hyper-CR equation, and show how any solution to this equation gives rise to a supersymmetric Einstein–Maxwell cosmological space–time in (3+1)-dimensions. © 2018 ...
• Solutions of D = 4 gauged pseudo-supergravity 

  Gutowski, Jan B.; Sabra, Wafic A. (Institute of Physics Publishing, 2019)

  The techniques of spinorial geometry are used to classify solutions admitting Killing spinors in the theory of minimal anti-de Sitter N = 2, D = 4 supergravity, where the gauge kinetic term comes with the opposite sign. ...
• Spinorial geometry, off-shell Killing spinor identities and higher derivative 5D supergravities 

  Bonetti, Federico; Klemm, Dietmar Silke; Sabra, Wafic A.; Sloane, Peter (Springer Verlag, 2018)

  Killing spinor identities relate components of equations of motion to each other for supersymmetric backgrounds. The only input required is the field content and the supersymmetry transformations of the fields, as long as ...
• Einstein-Weyl spaces and near-horizon geometry 

  Dunajski, Maciej; Gutowski, Jan B.; Sabra, Wafic A. (Institute of Physics Publishing, 2017)

  We show that a class of solutions of minimal supergravity in five dimensions is given by lifts of three-dimensional Einstein-Weyl structures of hyper-CR type. We characterise this class as most general near-horizon limits ...
• On the Isoperimetric Inequality for the Magnetic Robin Laplacian with Negative Boundary Parameter 

  Kachmar, Ayman; Lotoreichik, Vladimir Yu (Springer, 2022)

  We consider the magnetic Robin Laplacian with a negative boundary parameter on a bounded, planar C2-smooth domain. The respective magnetic field is homogeneous. Among a certain class of domains, we prove that the disk ...
• 10D to 4D Euclidean supergravity over a Calabi-Yau three-fold 

  Sabra, Wafic A.; Vaughan, Owen (Institute of Physics Publishing, 2016)

  We dimensionally reduce the bosonic sector of 10D Euclidean type IIA supergravity over a Calabi-Yau three-fold. The resulting theory describes the bosonic sector of 4D, = 2 Euclidean supergravity coupled to vector- and ...
• Phantom metrics with Killing spinors 

  Sabra, Wafic A. (Elsevier, 2015)

  We study metric solutions of Einstein-anti-Maxwell theory admitting Killing spinors. The analogue of the IWP metric which admits a space-like Killing vector is found and is expressed in terms of a complex function satisfying ...
• Euclidean supergravity in five dimensions 

  Sabra, Wafic A.; Vaughan, Owen (Elsevier B.V., 2016)

  We construct a 5D, N=2 Euclidean theory of supergravity coupled to vector multiplets. Upon reducing this theory over a circle we recover the action of 4D, N=2 Euclidean supergravity coupled to vector multiplets. © 2016 The ...
• Index theory and supersymmetry of 5D horizons 

  Grover, Jai; Gutowski, Jan B.; Papadopoulos, George; Sabra, Wafic A. (Springer Verlag, 2014)

  We prove that the near-horizon geometries of minimal gauged five-dimensional supergravity preserve at least half of the supersymmetry. If the near-horizon geometries preserve a larger fraction, then they are locally isometric ...
• No fermionic wigs for BPS attractors in 5 dimensions 

  Gentile, Lorenzo G.C.; Grassi, Pietro Antonio; Marrani, Alessio; Mezzalira, Andrea; Sabra, Wafic A. (Elsevier, 2014)

  We analyze the fermionic wigging of 1/2-BPS (electric) extremal black hole attractors in N=2, D = 5 ungauged Maxwell-Einstein supergravity theories, by exploiting anti-Killing spinors supersymmetry transformations. Regardless ...
• Non-existence of supersymmetric AdS5 black rings 

  Grover, Jai; Gutowski, Jan B.; Sabra, Wafic A. (Springer Verlag, 2014)

  It has been proven in arXiv:1303.0853 that all regular supersymmetric near-horizon geometries in minimal five-dimensional gauged supergravity admit automatic supersymmetry enhancement. Using this result, the integrability ...
• Mimetic Horava and surface terms 

  Malaeb, O.; Saghir, Chireen A. (Springer, 2023)

  We consider mimetic Horava gravity, where the scalar field of mimetic gravity was used in the construction of diffeomorphism invariant models reducing to Horava gravity in the synchronous gauge. It will be shown that the ...
• Curvature tensor in discrete gravity 

  Chamseddine, Ali H.; Malaeb, O.; Najem, Sara A. (Institute for Ionics, 2023)

  We study numerically the curvature tensor in a three-dimensional discrete space. Starting from the continuous metric of a three-sphere, we transformed it into a discrete space using three integers n1, n2 , and n3 . The ...
• A framework for reconstructing transmission networks in infectious diseases 

  Najem, Sara A.; Monni, Stefano; Hatoum, Rola; Sweidan, Hawraa; Faour, Ghaleb; Abdallah, Chadi; Ghosn, Nada; Hassan, Hamad; Touma, Jihad R. (Springer Science and Business Media Deutschland GmbH, 2022)

  In this paper, we propose a general framework for the reconstruction of the underlying cross-regional transmission network contributing to the spread of an infectious disease. We employ an autoregressive model that allows ...
• Scalar curvature in discrete gravity 

  Chamseddine, Ali H.; Malaeb, O.; Najem, Sara A. (Springer Science and Business Media Deutschland GmbH, 2022)

  We focus on studying, numerically, the scalar curvature tensor in a two-dimensional discrete space. The continuous metric of a two-sphere is transformed into that of a lattice using two possible slicings. In the first, we ...
• Laplace surface dynamics, revisited: Satellites, exoplanets, and debris with distant, eccentric companions 

  Farhat, Mohammad A.; Touma, Jihad R. (Oxford University Press, 2021)

  To date, studies of Laplace surface dynamics have concerned themselves with test particle orbits of fixed shape and orientation in the combined field of an oblate central body (to which the particle is bound) and a distant, ...

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