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140
Towards strange metallic holography
"... We initiate a holographic model building approach to ‘strange metallic ’ phenomenology. Our model couples a neutral Lifshitzinvariant quantum critical theory, dual to a bulk gravitational background, to a finite density of gapped probe charge carriers, dually described by Dbranes. In the physical ..."
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We initiate a holographic model building approach to ‘strange metallic ’ phenomenology. Our model couples a neutral Lifshitzinvariant quantum critical theory, dual to a bulk gravitational background, to a finite density of gapped probe charge carriers, dually described by Dbranes. In the physical regime of temperature much lower than the charge density and gap, we exhibit anomalous scalings of the temperature and frequency dependent conductivity. Choosing the dynamical critical exponent z appropriately we can match the nonFermi liquid scalings, such as linear resistivity, observed in strange metal regimes. As part of our investigation we outline three distinct string theory realizations of Lifshitz geometries: from F theory, from polarised branes, and from a gravitating charged Fermi gas. We also identify general features of renormalisation group flow in Lifshitz theories, such as the appearance of relevant chargecharge interactions when z ≥ 2. We outline a program to extend this model building approach to other anomalous observables of
Introduction to Holographic Superconductors
, 2010
"... Abstract These lectures give an introduction to the theory of holographic superconductors. These are superconductors that have a dual gravitational description using gauge/gravity duality. After introducing a suitable gravitational theory, we ..."
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Cited by 90 (3 self)
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Abstract These lectures give an introduction to the theory of holographic superconductors. These are superconductors that have a dual gravitational description using gauge/gravity duality. After introducing a suitable gravitational theory, we
Electron stars for holographic metallic criticality
 Phys.Rev. D83 (2011) 046003, arXiv:1008.2828 [hepth
"... We refer to the ground state of a gravitating, charged ideal fluid of fermions held at a finite chemical potential as an ‘electron star’. In a holographic setting, electron stars are candidate gravity duals for strongly interacting finite fermion density systems. We show how electron stars develop a ..."
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Cited by 58 (7 self)
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We refer to the ground state of a gravitating, charged ideal fluid of fermions held at a finite chemical potential as an ‘electron star’. In a holographic setting, electron stars are candidate gravity duals for strongly interacting finite fermion density systems. We show how electron stars develop an emergent Lifshitz scaling at low energies. This IR scaling region is a consequence of the two way interaction between emergent quantum critical bosonic modes and the finite density of fermions. By integrating from the IR region to an asymptotically AdS4 spacetime, we compute basic properties of the electron stars, including their electrical conductivity. We emphasize the challenge of connecting UV and IR physics in strongly interacting finite density systems. ar
Wilsonian Approach to Fluid/Gravity Duality
 JHEP 1103 (2011) 141 [arXiv:1006.1902 [hepth
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Holographic quantum criticality from multitrace deformations
"... We explore the consequences of multitrace deformations in applications of gaugegravity duality to condensed matter physics. We find that they introduce a powerful new “knob ” that can implement spontaneous symmetry breaking, and can be used to construct a new type of holographic superconductor. Th ..."
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Cited by 26 (3 self)
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We explore the consequences of multitrace deformations in applications of gaugegravity duality to condensed matter physics. We find that they introduce a powerful new “knob ” that can implement spontaneous symmetry breaking, and can be used to construct a new type of holographic superconductor. This knob can be tuned to drive the critical temperature to zero, leading to a new quantum critical point. We calculate nontrivial critical exponents, and show that fluctuations of the order parameter are ‘locally ’ quantum critical in the disordered phase. Most notably the dynamical critical exponent is determined by the dimension of an operator at the critical point. We argue that the results are robust against quantum corrections and discuss various generalizations. ar X iv
A Holographic Quantum Critical Point at Finite Magnetic Field and Finite Density
 JHEP
, 2010
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Holography of Charged Dilaton Black Holes
 Black Branes,” JHEP
, 2010
"... Abstract: We study charged dilaton black branes in AdS4. Our system involves a dilaton φ coupled to a Maxwell field Fµν with dilatondependent gauge coupling, 1 g2 = f 2(φ). First, we find the solutions for extremal and near extremal branes through a combination of analytical and numerical technique ..."
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Cited by 20 (4 self)
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Abstract: We study charged dilaton black branes in AdS4. Our system involves a dilaton φ coupled to a Maxwell field Fµν with dilatondependent gauge coupling, 1 g2 = f 2(φ). First, we find the solutions for extremal and near extremal branes through a combination of analytical and numerical techniques. The near horizon geometries in the simplest cases, where f(φ) = eαφ, are Lifshitzlike, with a dynamical exponent z determined by α. The black hole thermodynamics varies in an interesting way with α, but in all cases the entropy is vanishing and the specific heat is positive for the near extremal solutions. We then compute conductivity in these backgrounds. We find that somewhat surprisingly, the AC conductivity vanishes like ω2 at T = 0 independent of α. We also explore the charged black brane physics of several other classes of gaugecoupling functions f(φ). In addition to possible applications in AdS/CMT, the extremal black branes are of interest from the point of view of the attractor mechanism. The near horizon geometries for these branes are universal, independent of the asymptotic values of the moduli, and describe generic classes of endpoints for attractor flows which are different from AdS2 ×R2. ar X iv
Lectures on hydrodynamic fluctuations in relativistic theories, J.Phys. A45
, 2012
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BMS/GCA Redux: Towards Flatspace Holography from NonRelativistic
 Symmetries,” JHEP 1210, 092 (2012) [arXiv:1203.5795 [hepth
"... Abstract: The asymptotic group of symmetries at null infinity of flat spacetimes in three and four dimensions is the infinite dimensional BondiMetznerSachs (BMS) group. This has recently been shown to be isomorphic to nonrelativistic conformal algebras in one lower dimension, the Galilean Conform ..."
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Abstract: The asymptotic group of symmetries at null infinity of flat spacetimes in three and four dimensions is the infinite dimensional BondiMetznerSachs (BMS) group. This has recently been shown to be isomorphic to nonrelativistic conformal algebras in one lower dimension, the Galilean Conformal Algebra (GCA) in 2d and a closely related nonrelativistic algebra in 3d [1]. We provide a better understanding of this surprising connection by providing a spacetime interpretation in terms of a novel contraction. The 2d GCA, obtained from a linear combination of two copies of the Virasoro algebra, is generically nonunitary. The unitary subsector previously constructed had trivial correlation functions. We consider a representation obtained from a different linear combination of the Virasoros, which is relevant to the relation with the BMS algebra in three dimensions. This is realised by a new spacetime contraction of the parent algebra. We show that this representation has a unitary subsector with interesting correlation functions. We discuss implications for the BMS/GCA correspondence and show that the flat space limit actually induces precisely this contraction on the boundary conformal field theory. We also discuss aspects of asymptotic symmetries and the consequences of this contraction in higher dimensions. ar X iv
Extremal Horizons with Reduced Symmetry: Hyperscaling Violation, Stripes, and a Classification for the Homogeneous Case
 JHEP 1303 (2013) 126 [1212.1948]. – 55
"... 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 propos ..."
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Cited by 14 (3 self)
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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 ar X iv