G. Papadopoulos

King's College London, Londinium, England, United Kingdom

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Publications (102)380.85 Total impact

  • J. B. Gutowski, G. Papadopoulos
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    ABSTRACT: We give a systematic description of all warped $AdS_n$ and ${\mathbb{R}}^{n-1,1}$ backgrounds of M-theory and identify the a priori number of supersymmetries that these backgrounds preserve. In particular, we show that $AdS_n$ backgrounds preserve $N= 2^{[{n\over2}]} k$ for $n\leq4$ and $N= 2^{[{n\over2}]+1} k$ for $4<n\leq 7$ supersymmetries while ${\mathbb{R}}^{n-1,1}$ backgrounds preserve $N= 2^{[{n\over2}]} k$ for $n\leq4$ and $N= 2^{[{n+1\over2}]} k$ for $4<n\leq7$, supersymmetries. Furthermore for $AdS_n$ backgrounds that satisfy the requirements for the maximum principle to hold, we show that the Killing spinors can be identified with the zero modes of Dirac-like operators on $M^{11-n}$ coupled to fluxes thus establishing a new class of Lichnerowicz type theorems. We also demonstrate that the Killing spinors of generic warped $AdS_n$ backgrounds do not factorize into products of Killing spinors on $AdS_n$ and Killing spinors on the transverse space.
    07/2014;
  • M. Akyol, G. Papadopoulos
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    ABSTRACT: The spinorial geometry method of solving Killing spinor equations is reviewed as it applies to 6-dimensional (1,0) supergravity. In particular, it is explained how the method is used to identify both the fractions of supersymmetry preserved by and the geometry of all supersymmetric backgrounds. Then two applications are described to systems that exhibit superconformal symmetry. The first is the proof that some 6-dimensional black hole horizons are locally isometric to $AdS_3\times \Sigma^3$, where $\Sigma^3$ is diffeomeorphic to $S^3$. The second one is a description of all supersymmetric solutions of 6-dimensional (1,0) superconformal theories and in particular of their brane solitons.
    Classical and Quantum Gravity 04/2014; 31(12). · 3.56 Impact Factor
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    G. Papadopoulos
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    ABSTRACT: We investigate the patching of double and exceptional field theories. In double field theory the patching conditions imposed on the spacetime 3-form field strength $H$ after solving the strong section condition imply that $H$ is exact. A similar conclusion can be reached for the form field strengths of exceptional field theories after some plausive assumptions are made on the relation between the transition functions of the additional coordinates and the patching data of the form field strengths. We illustrate the issues that arise, and explore several alternative options including the introduction of C-folds and of the topological geometrisation condition.
    02/2014;
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    Ulf Gran, George Papadopoulos, Christian von Schultz
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    ABSTRACT: IIA supergravity backgrounds preserving one supersymmetry locally admit four types of Killing spinors distinguished by the orbits of $Spin(9,1)$ on the space of spinors. We solve the Killing spinor equations of IIA supergravity with and without cosmological constant for Killing spinors representing two of these orbits, with isotropy groups $Spin(7)$ and $Spin(7)\ltimes\mathbb{R}^8$. In both cases, we identify the geometry of spacetime and express the fluxes in terms of the geometry. We find that the geometric constraints of backgrounds with a $Spin(7)\ltimes\mathbb{R}^8$ invariant Killing spinor are identical to those found for heterotic backgrounds preserving one supersymmetry.
    01/2014;
  • M. Akyol, G. Papadopoulos
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    ABSTRACT: We solve the Killing spinor equations of 6-dimensional (1,0) superconformal theories which include hyper-multiplets in all cases. We show that the solutions preserve 1,2,3,4 and 8 supersymmetries. We find models with self-dual string solitons which are smooth and supported by instantons with an arbitrary gauge group, and 3-brane solitons as expected from the M-brane intersection rules.
    07/2013;
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    U. Gran, J. Gutowski, G. Papadopoulos
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    ABSTRACT: We show that the number of supersymmetries of IIB black hole horizons is N=2 N_- + 2 index(D_\lambda), where index(D_\lambda) is the index of the Dirac operator twisted with the line bundle \lambda^{1/2} of IIB scalars, and N_- is the dimension of the kernel of a horizon Dirac operator which depends on IIB fluxes. Therefore, all IIB horizons preserve an even number of supersymmetries. In addition if the horizons have non-trivial fluxes and N_- is nonzero, then index(D_\lambda) is non-negative, and the horizons admit an sl(2,R) symmetry subalgebra. This provides evidence that all such horizons have an AdS/CFT dual. Furthermore if the orbits of sl(2,R) are two-dimensional, the IIB horizons are warped products AdS_2 X S.
    Journal of High Energy Physics 06/2013; 2013(5). · 5.62 Impact Factor
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    U. Gran, J. Gutowski, G. Papadopoulos
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    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 8-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.
    Classical and Quantum Gravity 04/2013; · 3.56 Impact Factor
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    J. Grover, J. B. Gutowski, G. Papadopoulos, W. A. Sabra
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    ABSTRACT: 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 to AdS5. Our proof is based on Lichnerowicz type theorems for two horizon Dirac operators constructed from the supercovariant connection restricted to the horizon sections, and on an application of the index theorem. An application is that all five-dimensional horizons admit an sl(2,R) symmetry subalgebra.
    03/2013;
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    G. Papadopoulos
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    ABSTRACT: We find under some mild assumptions that the most general potential of 1-dimensional conformal systems with time independent couplings is expressed as $V=V_0+V_1$, where $V_0$ is a homogeneous function with respect to a homothetic motion in configuration space and $V_1$ is determined from an equation with source a homothetic potential. Such systems admit at most an $SL(2,\bR)$ conformal symmetry which, depending on the couplings, is embedded in Diff(R)$ in three different ways. In one case, $SL(2,\bR)$ is also embedded in Diff(S^1). Examples of such models include those with potential $V=\alpha x^2+\beta x^{-2}$ for arbitrary couplings $\alpha$ and $\beta$, the Calogero models with harmonic oscillator couplings and non-linear models with suitable metrics and potentials. In addition, we give the conditions on the couplings for a class of gauge theories to admit a $SL(2,\bR)$ conformal symmetry. We present examples of such systems with general gauge groups and global symmetries that include the isometries of $AdS_2 x S^3$ and $AdS_2 x S^3 x S^3$ which arise as backgrounds in $AdS_2/CFT_1$.
    Classical and Quantum Gravity 10/2012; 30(7). · 3.56 Impact Factor
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    Mehmet Akyol, George Papadopoulos
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    ABSTRACT: We solve the Killing spinor equations of 6-dimensional (1,0) superconformal theories in all cases. In particular, we derive the conditions on the fields imposed by the Killing spinor equations and demonstrate that these depend on the isotropy group of the Killing spinors. We focus on the models proposed by Samtleben et al in \cite{ssw} and find that there are solutions preserving 1,2, 4 and 8 supersymmetries. We also explore the solutions which preserve 4 supersymmetries and find that many models admit string and 3-brane solitons as expected from the M-brane intersection rules. The string solitons are smooth regulated by the moduli of instanton configurations.
    Journal of High Energy Physics 04/2012; 2012(7). · 5.62 Impact Factor
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    M Akyol, G Papadopoulos
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    ABSTRACT: We show that the supersymmetric near horizon black hole geometries of six-dimensional supergravity coupled to any number of scalar and tensor multiplets are either locally AdS3 × Σ3, where Σ3 is a homology 3-sphere, or , where is a 4-manifold whose geometry depends on the hypermultiplet scalars. In both cases, we find that the tensorini multiplet scalars are constant and the associated 3-form field strengths vanish. We also demonstrate that the AdS3 × Σ3 horizons preserve two, four and eight supersymmetries. For horizons with four supersymmetries, Σ3 is in addition a non-trivial circle fibration over a topological 2-sphere. The near horizon geometries preserving eight supersymmetries are locally isometric to either AdS3 × S3 or R1, 1 × T4. Moreover, we show that the horizons preserve one, two and four supersymmetries and the geometry of is Riemann, Kähler and hyper-Kähler, respectively.
    Classical and Quantum Gravity 02/2012; 29(5):055002. · 3.56 Impact Factor
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    G. Papadopoulos
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    ABSTRACT: We determine the geometry of the target spaces of supersymmetric non-relativistic particles with torsion and magnetic couplings, and with symmetries generated by the fundamental forms of G-structures for $G= U(n), SU(n), Sp(n), Sp(n)\cdot Sp(1), G_2$ and $Spin(7)$. We find that the Killing-Yano equation, which arises as a condition for the invariance of the worldline action, does not always determine the torsion coupling uniquely in terms of the metric and fundamental forms. We show that there are several connections with skew-symmetric torsion for $G=U(n), SU(n)$ and $G_2$ that solve the invariance conditions. We describe all these compatible connections for each of the $G$-structures and explain the geometric nature of the couplings.
    Classical and Quantum Gravity 11/2011; 29(11). · 3.56 Impact Factor
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    U.gran, J.gutowski, G.papadopoulos, D.roest
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    ABSTRACT: We review some aspects of the spinorial geometry approach to the classification of supersymmetric solutions of supergravity theories. In particular, we explain how spinorial geometry can be used to express the Killing spinor equations in terms of a linear system for the fluxes and the geometry of spacetime. The solutions of this linear system express some of the fluxes in terms of the spacetime geometry and determine the conditions on the spacetime geometry imposed by supersymmetry. We also present some of the recent applications like the classification of maximally supersymmetric G-backgrounds in IIB, this includes the most general pp-wave solution preserving 1/2 supersymmetry, and the classification of N = 31 backgrounds in ten and eleven dimensions.
    Modern Physics Letters A 11/2011; 22(01). · 1.11 Impact Factor
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    U. Gran, J. Gutowski, G. Papadopoulos
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    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 8-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.
    Classical and Quantum Gravity 10/2011; · 3.56 Impact Factor
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    J. Gutowski, G. Papadopoulos
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    ABSTRACT: We determine the geometry of all static black hole horizons of M-theory preserving at least one supersymmetry. We demonstrate that all such horizons are either warped products R^{1,1} *_w S or AdS_2 *_w S, where S admits an appropriate Spin(7) or SU(4) structure respectively; and we derive the conditions imposed by supersymmetry on these structures. We show that for electric static horizons with Spin(7) structure, the near horizon geometry is a product R^{1,1} * S, where S is a compact Spin(7) holonomy manifold. For electric static solutions with SU(4) structure, we show that the horizon section S is a circle fibration over an 8-dimensional Kahler manifold which satisfies an additional condition involving the Ricci scalar and the length of the Ricci tensor. Solutions include AdS_2 * S^3 * CY_6 as well as many others constructed from taking the 8-dimensional Kahler manifold to be a product of Kahler-Einstein and Calabi-Yau spaces.
    Journal of High Energy Physics 06/2011; · 5.62 Impact Factor
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    U. Gran, J. Gutowski, G. Papadopoulos
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    ABSTRACT: We classify under some assumptions the IIB black hole horizons with 5-form flux preserving more than 2 supersymmetries. We find that the spatial horizon sections with non-vanishing flux preserving 4 supersymmetries are locally isometric either to S^1 * S^3 * T^4 or to S^1 * S^3 * K_3 and the associated near horizon geometries are locally isometric to AdS_3 * S^3 * T^4 and AdS_3 * S^3 * K_3$, respectively. The near horizon geometries preserving more than 4 supersymmetries are locally isometric to R^{1,1} * T^8.
    Journal of High Energy Physics 04/2011; 9. · 5.62 Impact Factor
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    M Akyol, G Papadopoulos
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    ABSTRACT: We solve the Killing spinor equations of six-dimensional (1, 0)-supergravity coupled to any number of tensor, vector and scalar multiplets in all cases. The isotropy groups of Killing spinors are , , , Sp(1)(2), U(1)(4) and {1}(8), where in parenthesis is the number of supersymmetries preserved in each case. If the isotropy group is non-compact, the spacetime admits a parallel null 1-form with respect to a connection with torsion given by the 3-form field strength of the gravitational multiplet. The associated vector field is Killing and the 3-form is determined in terms of the geometry of spacetime. The case admits a descendant solution preserving three out of four supersymmetries due to the hyperini Killing spinor equation. If the isotropy group is compact, the spacetime admits a natural frame constructed from 1-form spinor bi-linears. In the Sp(1) and U(1) cases, the spacetime admits three and four parallel 1-forms with respect to the connection with torsion, respectively. The associated vector fields are Killing and under some additional restrictions the spacetime is a principal bundle with fibre a Lorentzian Lie group. The conditions imposed by the Killing spinor equations on all other fields are also determined.
    Classical and Quantum Gravity 04/2011; 28(10):105001. · 3.56 Impact Factor
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    U. Gran, J. Gutowski, G. Papadopoulos
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    ABSTRACT: We investigate the near horizon geometry of IIB supergravity black holes with non-vanishing 5-form flux preserving at least two supersymmetries. We demonstrate that there are three classes of solutions distinguished by the choice of Killing spinors. We find that the spatial horizon sections of the class of solutions with an SU(4) invariant pure Killing spinor are hermitian manifolds and admit a hidden Kahler with torsion (KT) geometry compatible with the SU(4) structure. Moreover the Bianchi identity of the 5-form, which also implies the field equations, can be expressed in terms of the torsion H as d(\omega\wedge H)=\partial\bar\partial \omega^2=0, where omega is a Hermitian form. We give several examples of near horizon geometries which include group manifolds, group fibrations over KT manifolds and uplifted geometries of lower dimensional black holes. Furthermore, we show that the class of solutions associated with a Spin(7) invariant spinor is locally a product R^{1,1} x S, where S is a holonomy Spin(7) manifold.
    Journal of High Energy Physics 01/2011; 2011(5). · 5.62 Impact Factor
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    G Papadopoulos
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    ABSTRACT: We simplify the classification of supersymmetric solutions with compact holonomy of the Killing spinor equations of heterotic supergravity using the field equations and the additional assumption that the 3-form flux is closed. We determine all the fractions of supersymmetry that the solutions preserve and find that there is a restriction on the number of supersymmetries which depends on the isometry group of the background. We examine the geometry of spacetime in all cases. We find that the supersymmetric solutions of heterotic supergravity are associated with a large number of geometric structures which include seven-dimensional manifolds with G2 structure, six-dimensional complex and almost complex manifolds, and four-dimensional hyper-Kähler, Kähler and anti-self-dual Weyl manifolds.
    Classical and Quantum Gravity 04/2010; 27(12):125008. · 3.56 Impact Factor
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    J. Gutowski, G. Papadopoulos
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    ABSTRACT: All supersymmetric , D = 4 supergravity horizons have toroidal or spherical topology, irrespective of whether the black hole preserves any supersymmetry.
    Journal of High Energy Physics 01/2010; 2010(11):1-18. · 5.62 Impact Factor

Publication Stats

3k Citations
380.85 Total Impact Points

Institutions

  • 1987–2013
    • King's College London
      • Department of Mathematics
      Londinium, England, United Kingdom
  • 2008
    • Chalmers University of Technology
      • Department of Fundamental Physics
      Göteborg, Vaestra Goetaland, Sweden
  • 1993–2006
    • University of Cambridge
      • Department of Applied Mathematics and Theoretical Physics
      Cambridge, England, United Kingdom
    • University of Melbourne
      • School of Physics
      Melbourne, Victoria, Australia
  • 1997
    • Stanford University
      • Department of Physics
      Palo Alto, California, United States
  • 1996
    • University of Groningen
      • Centre for Theoretical Physics (CTN)
      Groningen, Groningen, Netherlands
  • 1988–1996
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
  • 1994
    • Universität Hamburg
      • II. Institut für Theoretische Physik
      Hamburg, Hamburg, Germany
  • 1986–1992
    • Imperial College London
      • Department of Physics
      Londinium, England, United Kingdom
  • 1991
    • Queen Mary, University of London
      Londinium, England, United Kingdom