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Denef, Frederik

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Denef

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Frederik

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Denef, Frederik
Author's Publications: search.filters.isAuthorOfPublication.4b9c823e-4ae5-484e-93e0-289c96346f9f

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Now showing 1 - 10 of 28
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    Exact Solutions for Supersymmetric Stationary Black Hole Composites
    (Springer, 2011) Bates, Brandon; Denef, Frederik
    Four dimensional N = 2 supergravity has regular, stationary, asymptotically flat BPS solutions with intrinsic angular momentum, describing bound states of separate extremal black holes with mutually nonlocal charges. Though the existence and some properties of these solutions were established some time ago, fully explicit analytic solutions were lacking thus far. In this note, we fill this gap. We show in general that explicit solutions can be constructed whenever an explicit formula is known in the theory at hand for the Bekenstein-Hawking entropy of a single black hole as a function of its charges, and illustrate this with some simple examples. We also give an example of moduli-dependent black hole entropy.
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    Wall-Crossing from Supersymmetric Galaxies
    (Springer, 2012) Andriyash, Evgeny; Denef, Frederik; Jafferis, Daniel; Moore, Gregory W.
    We give an elementary physical derivation of the Kontsevich-Soibelman wall crossing formula, valid for any theory with a 4d N = 2 supergravity description. Our argument leads to a slight generalization of the formula, which relates monodromy to the BPS spectrum.
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    Split States, Entropy Enigmas, Holes and Halos
    (Springer, 2011) Denef, Frederik; Moore, Gregory W.
    We investigate degeneracies of BPS states of D-branes on compact Calabi-Yau manifolds. We develop a factorization formula for BPS indices using attractor flow trees associated to multicentered black hole bound states. This enables us to study background dependence of the BPS spectrum, to compute explicitly exact indices of various nontrivial D-brane systems, and to clarify the subtle relation of Donaldson-Thomas invariants to BPS indices of stable D6-D2-D0 states, realized in supergravity as “hole halos.” We introduce a convergent generating function for D4 indices in the large CY volume limit, and prove it can be written as a modular average of its polar part, generalizing the fareytail expansion of the elliptic genus. We show polar states are “split” D6-anti-D6 bound states, and that the partition function factorizes accordingly, leading to a refined version of the OSV conjecture. This differs from the original conjecture in several aspects. In particular we obtain a nontrivial measure factor \(g^{−2}_{top} e^{−K}\) and find factorization requires a cutoff. We show that the main factor determining the cutoff and therefore the error is the existence of “swing states” — D6 states which exist at large radius but do not form stable D6-anti-D6 bound states. We point out a likely breakdown of the OSV conjecture at small \(g_{top}\) (in the large background CY volume limit), due to the surprising phenomenon that for sufficiently large background Kähler moduli, a charge \(\Lambda \Gamma\) supporting single centered black holes of entropy \(\sim \Lambda^2 S(\Gamma)\) also admits two-centered BPS black hole realizations whose entropy grows like \(\Lambda^3\) when \(\Lambda \rightarrow \infty\).
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    Hot Halos and Galactic Glasses (Carbonado)
    (Springer Verlag, 2012) Anninos, Dionysios; Anous, Tarek; Barandes, Jacob; Denef, Frederik; Gaasbeek, Bram
    We initiate a systematic study of the state space of non-extremal, stationary black hole bound states in four-dimensional \(N\) = 2 supergravity. Specifically, we show that an exponential multitude of classically stable "halo" bound states can be formed between large finite temperature D4-D0 black hole cores and much smaller, arbitrarily charged black holes at the same temperature. We map out in full the regions of existence for thermodynamically stable and metastable bound states in terms of the core's charges and temperature, as well as the region of stability of the core itself. Several features of these systems, such as a macroscopic configurational entropy and exponential relaxation timescales, are similar to those of the extended family of glasses. We draw parallels between the two with a view toward understanding complex systems in fundamental physics.
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    Black Hole Determinants and Quasinormal Modes
    (Institute of Physics, 2010) Denef, Frederik; Hartnoll, Sean; Sachdev, Subir
    We derive an expression for functional determinants in thermal spacetimes as a product over the corresponding quasinormal modes. As simple applications we give efficient computations of scalar determinants in thermal AdS, BTZ black hole and de Sitter spacetimes. We emphasize the conceptual utility of our formula for discussing '1/N' corrections to strongly coupled field theories via the holographic correspondence.
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    Landscape of Superconducting Membranes
    (American Physical Society, 2009) Denef, Frederik; Hartnoll, Sean
    The AdS/CFT correspondence may connect the landscape of string vacua and the `atomic landscape' of condensed matter physics. We study the stability of a landscape of IR fixed points of N=2 large N gauge theories in 2+1 dimensions, dual to Sasaki-Einstein compactifications of M theory, towards a superconducting state. By exhibiting instabilities of charged black holes in these compactifications, we show that many of these theories have charged operators that condense when the theory is placed at a finite chemical potential. We compute a statistical distribution of critical superconducting temperatures for a subset of these theories. With a chemical potential of one milliVolt, we find critical temperatures ranging between 0.24 and 165 degrees Kelvin.
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    Orientiholes
    (Springer, 2010) Denef, Frederik; Esole, Mboyo; Padi, Megha
    By T-dualizing space-filling D-branes in 4d IIB orientifold compactifications along the three non-internal spatial directions, we obtain black hole bound states living in a universe with a gauged spatial reflection symmetry. We call these objects orientiholes. The gravitational entropy of various IIA orientihole configurations provides an “experimental” estimate of the number of vacua in various sectors of the IIB landscape. Furthermore, basic physical properties of orientiholes map to (sometimes subtle) microscopic features, thus providing a useful alternative viewpoint on a number of issues arising in D-brane model building. More generally, we give orientihole generalizations of recently derived wall crossing formulae, and conjecture a relation to the topological string analogous to the OSV conjecture, but with a linear rather than a quadratic identification of partition functions.
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    Quantum Oscillations and Black Hole Ringing
    (American Physical Society, 2009) Denef, Frederik; Hartnoll, Sean; Sachdev, Subir
    We show that strongly coupled field theories with holographic gravity duals at finite charge density and low temperatures can undergo de Haas–van Alphen quantum oscillations as a function of an external magnetic field. Exhibiting this effect requires computation of the one-loop contribution of charged bulk fermions to the free energy. The one-loop calculation is performed using a formula expressing determinants in black hole backgrounds as sums over quasinormal modes. At zero temperature, the periodic nonanalyticities in the magnetic susceptibility as a function of the inverse magnetic field depend on the low energy scaling behavior of fermionic operators in the field theory, and are found to be softer than in weakly coupled theories. We also obtain numerical and WKB results for the quasinormal modes of charged bosons in dyonic black hole backgrounds, finding evidence for nontrivial periodic behavior as a function of the magnetic field.
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    Distributions of Nonsupersymmetric Flux Vacua
    (Institute of Physics, 2005) Denef, Frederik; Douglas, Michael R.
    We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on Calabi-Yau manifolds, as in hep-th/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking.
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    Computational Complexity of the Landscape I
    (Elsevier, 2007) Denef, Frederik; Douglas, Michael R.
    We study the computational complexity of the physical problem of finding vacua of string theory which agree with data, such as the cosmological constant, and show that such problems are typically NP hard. In particular, we prove that in the Bousso–Polchinski model, the problem is NP complete. We discuss the issues this raises and the possibility that, even if we were to find compelling evidence that some vacuum of string theory describes our universe, we might never be able to find that vacuum explicitly. In a companion paper, we apply this point of view to the question of how early cosmology might select a vacuum.