Black holes in the Superworld
Some aspects of black holes in supersymmetric theories of gravity are reviewed and some recent results outlined.
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arXiv subjects
Laura Andrianopoli
Publications and source records attributed to Laura Andrianopoli.
D=4, N=2 Gauged Supergravity coupled to Vector-Tensor Multiplets
We construct the general four-dimensional N=2 supergravity theory coupled to vector and vector-tensor multiplets only. Consistency of the construction requires the introduction of the vector fields dual to those sitting in the same supermultiplets as the antisymmetric tensors, as well as the scalar fields dual to the tensors themselves. Gauge symmetries also involving these additional fields guarantee the correct counting of the physical degrees of freedom.
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D=4, N=2 Supergravity in the Presence of Vector-Tensor Multiplets and the Role of higher p-forms in the Framework of Free Differential Algebras
We thoroughly analyze at the bosonic level, in the framework of Free Differential Algebras (FDA), the role of 2-form potentials setting in particular evidence the precise geometric formulation of the anti-Higgs mechanism giving mass to the tensors. We then construct the (super)-FDA encoding the coupling of vector-tensor multiplets in D=4, N=2 supergravity, by solving the Bianchi identities in superspace and thus retrieving the full theory up to 3-fermions terms in the supersymmetry transformation laws, leaving the explicit construction of the Lagrangian to future work. We further explore the extension of the bosonic FDA in the presence of higher p-form potentials, focussing our attention to the particular case p=3, which would occur in the construction of D=5, N=2 supergravity where some of the scalars are properly dualized.
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First Order Description of Black Holes in Moduli Space
We show that the second order field equations characterizing extremal solutions for spherically symmetric, stationary black holes are in fact implied by a system of first order equations given in terms of a prepotential W. This confirms and generalizes the results in [14]. Moreover we prove that the squared prepotential function shares the same properties of a c-function and that it interpolates between M^2_{ADM} and M^2_{BR}, the parameter of the near-horizon Bertotti-Robinson geometry. When the black holes are solutions of extended supergravities we are able to find an explicit expression for the prepotentials, valid at any radial distance from the horizon, which reproduces all the attractors of the four dimensional N>2 theories. Far from the horizon, however, for N-even our ansatz poses a constraint on one of the U-duality invariants for the non-BPS solutions with Z \neq 0. We discuss a possible extension of our considerations to the non extremal case.
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Black-Hole Attractors in N=1 Supergravity
We study the attractor mechanism for N=1 supergravity coupled to vector and chiral multiplets and compute the attractor equations of these theories. These equations may have solutions depending on the choice of the holomorphic symmetric matrix f_{ΛΣ} which appears in the kinetic lagrangian of the vector sector. Models with non trivial electric-magnetic duality group which have or have not attractor behavior are exhibited. For a particular class of models, based on an N=1 reduction of homogeneous special geometries, the attractor equations are related to the theory of pure spinors.
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On the coupling of tensors to gauge fields: D=5, N=2 supergravity revisited
A general free differential algebra encoding the anti-Higgs mechanism among two-index antisymmetric tensors and gauge vectors is analyzed at the full group theoretical level. N=2 supergravity in five dimensions coupled to tensor, vector and hyper multiplets with all possible couplings included is reconsidered from this point of view. Within our approach, we find that some of the constraints on the couplings usually considered are too stringent and may in fact be relaxed. This generalization also affects the scalar potential.
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Extremal Black Holes in Supergravity
We present the main features of the physics of extremal black holes embedded in supersymmetric theories of gravitation, with a detailed analysis of the attractor mechanism for BPS and non-BPS black-hole solutions in four dimensions.
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Fluxes, supersymmetry breaking and gauged supergravity
We report on the gauged supergravity interpretation of certain compactifications of superstring theories with p-form fluxes turned on. We discuss in particular the interplay of duality symmetries in type IIB orientifolds and gauged isometries in the corresponding supergravity models. Turning on fluxes is generally described by the gauging of some nilpotent Lie group whose generators correspond to axion symmetries of R-R and N-S scalars.
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Supersymmetry reduction of N-extended supergravities in four dimensions
We consider the possible consistent truncation of N-extended supergravities to lower N' theories. The truncation, unlike the case of N-extended rigid theories, is non trivial and only in some cases it is sufficient just to delete the extra N-N' gravitino multiplets. We explore different cases (starting with N=8 down to N'\geq 2) where the reduction implies restrictions on the matter sector. We perform a detailed analysis of the interesting case N=2 \to N=1. This analysis finds applications in different contexts of superstring and M-theory dynamics.
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N=2 -> N=1 supergravity reduction in four dimensions
We discuss the reduction of N=2 supergravity to N=1, by a consistent truncation of the second gravitino multiplet.
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Matter Coupled F(4) Gauged Supergravity Lagrangian
We construct the so far unknown Lagrangian of D=6, N=2 F(4) Supergravity coupled to an arbitrary number of vector multiplets whose scalars span the coset manifold SO(4,n)/{SO(4) x SO(n)}. This is done first in the ungauged case and then extended to the compact gauging of SU(2) x G, where SU(2) is the R-symmetry diagonal subgroup of SU(2)_L x SU(2)_R = SO(4) and G is a compact subgroup of SO(n), n being the number of vector multiplets, and such that dim G = n. The knowledge of the Lagrangian allows in principle to refine the AdS_6/CFT_5 correspondence already discussed, as far as supersymmetric multiplets are concerned, in a previous related paper. With respect to the latter we also give a more exaustive treatment of the construction of the theory at the level of superspace Bianchi identities and in particular of the scalar potential.
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Non-Semisimple Gaugings of D=5 N=8 Supergravity
The recent construction of the non-semisimple gaugings of maximal D=5 supergravity is reported here. This construction is worked out in the so-called rheonomic approach, based on Free Differential Algebras and the solution of their Bianchi identities. In this approach the dualization mechanism between one-forms and two-forms is more transparent. The lagrangian is unnecessary since the field equations follow from closure of the supersymmetry algebra. These theories contain 12-r self-dual two-forms and 15+r gauge vectors, r of which are abelian and neutral. Such theories, whose existence has been proved and their supersymmetry algebra constructed, have potentially interesting properties in relation with domain wall solutions and the trapping of gravity.
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Isometric Embedding of BPS Branes in Flat Spaces with Two Times
We show how non-near horizon p-brane theories can be obtained from two embedding constraints in a flat higher dimensional space with 2 time directions. In particular this includes the construction of D3 branes from a flat 12-dimensional action, and M2 and M5 branes from 13 dimensions. The worldvolume actions are determined by constant forms in the higher dimension, reduced to the usual expressions by Lagrange multipliers. The formulation affords insight in the global aspects of the spacetime geometries and makes contact with recent work on two-time physics.
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``Non chiral'' primary superfields in the AdS_{d+1}/CFT_d correspondence
We consider some long multiplets describing bulk massive excitations of M-theory two-branes and IIB string three-branes which correspond to ``non chiral'' primary operators of the boundary OSp(8/4) and SU(2,2/4) superconformal field theories. Examples of such multiplets are the ``radial'' modes on the branes, including up to spin 4 excitations, which may be then considered as prototypes of states which are not described by the K-K spectrum of the corresponding supergravity theories on AdS_4 x S_7 and AdS_5 x S_5 respectively.
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K-K excitations on AdS_5 x S^5 as N=4 ``primary'' superfields
We show that the K-K spectrum of IIB string on AdS_5 x S_5 is described by ``twisted chiral'' N=4 superfields, naturally described in ``harmonic superspace'', obtained by taking suitable gauge singlets polynomials of the D3-brane boundary SU(n) superconformal field theory. To each p-order polynomial is associated a massive K-K short representation with 256 x 1/12 p^2(p^2 -1) states. The p=2 quadratic polynomial corresponds to the ``supercurrent multiplet'' describing the ``massless'' bulk graviton multiplet.
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Central charges, black-hole entropy and geometrical structure of N-extended supergravities in D=4
The derivation of absolute (moduli-independent) U-invariants for all N>2 extended supergravities at D=4 in terms of (moduli-dependent) central and matter charges is reported. These invariants give a general definition of the ``topological'' Bekenstein-Hawking entropy formula for extremal black-holes and reduce to the square of the black-hole ADM mass for ``fixed scalars'' which extremize the black-hole ``potential'' energy.
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