Publications (6)33.71 Total impact
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ABSTRACT: Classifying the zerotemperature ground states of quantum field theories with finite charge density is a very interesting problem. Via holography, this problem is mapped to the classification of extremal charged black brane geometries with antide Sitter asymptotics. In a recent paper [1], we proposed a Bianchi classification of the extremal nearhorizon geometries in five dimensions, in the case where they are homogeneous but, in general, anisotropic. Here, we extend our study in two directions: we show that Bianchi attractors can lead to new phases, and generalize the classification of homogeneous phases in a way suggested by holography. In the first direction, we show that hyperscaling violation can naturally be incorporated into the Bianchi horizons. We also find analytical examples of "striped" horizons. In the second direction, we propose a more complete classification of homogeneous horizon geometries where the natural mathematics involves real fouralgebras with three dimensional subalgebras. This gives rise to a richer set of possible nearhorizon geometries, where the holographic radial direction is nontrivially intertwined with field theory spatial coordinates. We find examples of several of the new types in systems consisting of reasonably simple matter sectors coupled to gravity, while arguing that others are forbidden by the Null Energy Condition. Extremal horizons in four dimensions governed by threealgebras or fouralgebras are also discussed.Journal of High Energy Physics 12/2012; 2013(3). · 5.62 Impact Factor 
Article: Entangled Dilaton Dyons
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ABSTRACT: EinsteinMaxwell theory coupled to a dilaton is known to give rise to extremal solutions with hyperscaling violation. We study the behaviour of these solutions in the presence of a small magnetic field. We find that in a region of parameter space the magnetic field is relevant in the infrared and completely changes the behaviour of the solution which now flows to an $AdS_2\times R^2$ attractor. As a result there is an extensive ground state entropy and the entanglement entropy of a sufficiently big region on the boundary grows like the volume. In particular, this happens for values of parameters at which the purely electric theory has an entanglement entropy growing with the area, $A$, like $A \log(A)$ which is believed to be a characteristic feature of a Fermi surface. Some other thermodynamic properties are also analysed and a more detailed characterisation of the entanglement entropy is also carried out in the presence of a magnetic field. Other regions of parameter space not described by the $AdS_2\times R^2$ end point are also discussed.Journal of High Energy Physics 08/2012; 2013(3). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Extremal black branes are of interest because they correspond to the ground states of field theories at finite charge density in gauge/gravity duality. The geometry of such a brane need not be translationally invariant in the spatial directions along which it extends. A less restrictive requirement is that of homogeneity, which still allows points along the spatial directions to be related to each other by symmetries. In this paper, we find large new classes of homogeneous but anisotropic extremal black brane horizons, which could naturally arise in gauge/gravity dual pairs. In 4+1 dimensional spacetime, we show that such homogeneous black brane solutions are classified by the Bianchi classification, which is well known in the study of cosmology, and fall into nine classes. In a system of Einstein gravity with negative cosmological term coupled to one or two massive Abelian gauge fields, we find solutions with an additional scaling symmetry, which could correspond to the nearhorizon geometries of such extremal black branes. These solutions realize many of the Bianchi classes. In one case, we construct the complete extremal solution which asymptotes to AdS space.Journal of High Energy Physics 01/2012; 2012(7). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study the twopoint function for fermionic operators in a class of strongly coupled systems using the gaugegravity correspondence. The gravity description includes a gauge field and a dilaton which determines the gauge coupling and the potential energy. Extremal black brane solutions in this system typically have vanishing entropy. By analyzing a charged fermion in these extremal black brane backgrounds we calculate the twopoint function of the corresponding boundary fermionic operator. We find that in some region of parameter space it is of Fermi liquid type. Outside this region no welldefined quasiparticles exist, with the excitations acquiring a nonvanishing width at zero frequency. At the transition, the twopoint function can exhibit nonFermi liquid behaviour.Journal of High Energy Physics 05/2011; 2012(1). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In this paper we study the spectrum of BPS operators/states in N=2 superconformal U(N) ChernSimonsmatter theories with adjoint chiral matter fields, with and without superpotential. The superconformal indices and conjectures on the full supersymmetric spectrum of the theories in the large N limit with up to two adjoint matter fields are presented. Our results suggest that some of these theories may have supergravity duals at strong coupling, while some others may be dual to higher spin theories of gravity at strong coupling. For the N=2 theory with no superpotential, we study the renormalization of Rcharge at finite 't Hooft coupling using "Zminimization". A particularly intriguing result is found in the case of one adjoint matter.Journal of High Energy Physics 04/2011; · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We consider two infinite families of NonSupersymmetric AdS 4 vacua, called Type 2) and Type 3) vacua, that arise in massive IIA supergravity with flux. We show that both families are perturbatively stable. We then examine nonperturbative decays of these vacua to other supersymmetric and nonsupersymmetric AdS 4 vacua mediated by instantons in the thin wall approximation. We find that many decays are ruled out since the tension of the interpolating domain wall is too big compared to the energy difference in AdS units. In fact, within our approximations no decays of Type 2) vacua are allowed, although some decays are only marginally forbidden. This can be understood in terms of a “pairing symmetry” in the landscape which relate Type 2) vacua with supersymmetric ones of the same energy. KeywordsFlux compactificationsSuperstring VacuaJournal of High Energy Physics 01/2010; 2010(7):147. · 5.62 Impact Factor
Publication Stats
134  Citations  
33.71  Total Impact Points  
Top Journals
Institutions

2012

Weizmann Institute of Science
Israel


2010–2012

Tata Institute of Fundamental Research
 Department of Theoretical Physics
Mumbai, Mahārāshtra, India
