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56
Quantum corrections to holographic entanglement entropy, JHEP 1311
, 2013
"... We consider entanglement entropy in quantum field theories with a gravity dual. In the gravity description, the leading order contribution comes from the area of a minimal surface, as proposed by RyuTakayanagi. Here we describe the one loop correction to this formula. The minimal surface divides t ..."
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Cited by 33 (2 self)
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We consider entanglement entropy in quantum field theories with a gravity dual. In the gravity description, the leading order contribution comes from the area of a minimal surface, as proposed by RyuTakayanagi. Here we describe the one loop correction to this formula. The minimal surface divides the bulk into two regions. The bulk loop correction is essentially given by the bulk entanglement entropy between these two bulk regions. We perform some simple checks of this proposal.ar X iv
Stellar spectroscopy: Fermions and holographic Lifshitz criticality
 JHEP
"... Electron stars are fluids of charged fermions in Antide Sitter spacetime. They are candidate holographic duals for gauge theories at finite charge density and exhibit emergent Lifshitz scaling at low energies. This paper computes in detail the field theory Green’s function GR(ω, k) of the gaugeinv ..."
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Cited by 21 (2 self)
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Electron stars are fluids of charged fermions in Antide Sitter spacetime. They are candidate holographic duals for gauge theories at finite charge density and exhibit emergent Lifshitz scaling at low energies. This paper computes in detail the field theory Green’s function GR(ω, k) of the gaugeinvariant fermionic operators making up the star. The Green’s function contains a large number of closely spaced Fermi surfaces, the volumes of which add up to the total charge density in accordance with the Luttinger count. Excitations of the Fermi surfaces are long lived for ω. kz. Beyond ω ∼ kz the fermionic quasiparticles dissipate strongly into the critical Lifshitz sector. Fermions near this critical dispersion relation give interesting contributions to the optical conductivity. ar X iv
Electron star birth: A continuous phase transition at nonzero density
"... We show that charged black holes in Antide Sitter spacetime can undergo a third order phase transition at a critical temperature in the presence of charged fermions. In the low temperature phase, a fraction of the charge is carried by a fermion fluid located a finite distance from the black hole. I ..."
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Cited by 19 (3 self)
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We show that charged black holes in Antide Sitter spacetime can undergo a third order phase transition at a critical temperature in the presence of charged fermions. In the low temperature phase, a fraction of the charge is carried by a fermion fluid located a finite distance from the black hole. In the zero temperature limit the black hole is no longer present and all charge is sourced by the fermions. The solutions exhibit the low temperature entropy density scaling s ∼ T 2/z anticipated from the emergent IR criticality of recently discussed electron stars. ar
Holographically smeared Fermi surface: Quantum oscillations and Luttinger count in electron stars,” [arXiv:1011.2502
"... We apply a small magnetic field to strongly interacting matter with a gravity dual description as an electron star. These systems are both metallic and quantum critical at low energies. The resulting quantum oscillations are shown to be of the KosevichLifshitz form characteristic of Fermi liquid th ..."
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Cited by 18 (3 self)
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We apply a small magnetic field to strongly interacting matter with a gravity dual description as an electron star. These systems are both metallic and quantum critical at low energies. The resulting quantum oscillations are shown to be of the KosevichLifshitz form characteristic of Fermi liquid theory. It is seen that only fermions at a single radius in the electron star contribute to the oscillations. We proceed to show that the Fermi surface area extracted from the quantum oscillations does not obey the simplest statement of the Luttinger theorem, that is, it is not universally proportional to the total charge density. It follows that our system is a nonFermi liquid that nonetheless exhibits KosevichLifshitz quantum oscillations. We explain how the Luttinger count is recovered via a field theoretic description involving a continuum of ‘smeared ’ fermionic excitations. ar
Locally critical umklapp scattering and holography,” arXiv:1201.3917 [hepth
"... Efficient momentum relaxation through umklapp scattering, leading to a power law in temperature d.c. resistivity, requires a significant low energy spectral weight at finite momentum. One way to achieve this is via a Fermi surface structure, leading to the wellknown relaxation rate Γ ∼ T 2. We obse ..."
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Cited by 8 (2 self)
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Efficient momentum relaxation through umklapp scattering, leading to a power law in temperature d.c. resistivity, requires a significant low energy spectral weight at finite momentum. One way to achieve this is via a Fermi surface structure, leading to the wellknown relaxation rate Γ ∼ T 2. We observe that local criticality, in which energies scale but momenta do not, provides a distinct route to efficient umklapp scattering. We show that umklapp scattering by an ionic lattice in a locally critical theory leads to Γ ∼ T 2∆kL. Here ∆kL ≥ 0 is the dimension of the (irrelevant or marginal) charge density operator J t(ω, kL) in the locally critical theory, at the lattice momentum kL. We illustrate this result with an explicit computation in locally critical theories described holographically via EinsteinMaxwell theory in Antide Sitter spacetime. We furthermore show that scattering by random impurities in these locally critical theories gives a universal Γ ∼ (log 1T)−1. ar
Charge Expulsion from Black Brane Horizons
 and Holographic Quantum Criticality in the Plane,” arXiv:1202.2085 [hepth
"... Quantum critical behavior in 2+1 dimensions is established via holographic methods in a 5+1dimensional Einstein gravity theory with gauge potential form fields of rank 1 and 2. These fields are coupled to one another via a trilinear ChernSimons term with strength k. The quantum phase transition ..."
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Cited by 7 (1 self)
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Quantum critical behavior in 2+1 dimensions is established via holographic methods in a 5+1dimensional Einstein gravity theory with gauge potential form fields of rank 1 and 2. These fields are coupled to one another via a trilinear ChernSimons term with strength k. The quantum phase transition is physically driven by the expulsion of the electric charge from inside the black brane horizon to the outside, where it gets carried by the gauge fields which acquire charge thanks to the ChernSimons interaction. At a critical value k = kc, zero temperature, and any finite value of the magnetic field, the IR behavior is governed by a nearhorizon Lifshitz geometry. The associated dynamical scaling exponent depends on the magnetic field. For k < kc, the flow towards low temperature is governed by a ReissnerNordstromlike black brane whose charge and entropy density are nonvanishing at zero temperature. For k> kc, the IR flow is towards the purely magnetic brane in AdS6. Its nearhorizon geometry is AdS4 × R2, so that the entropy density vanishes quadratically with temperature, and all charge is carried by the gauge fields outside of the horizon.
Holographic order parameter for charge fractionalization,” arXiv:1205.5291 [hepth
"... Nonlocal order parameters for deconfinement, such as the entanglement entropy and Wilson loops, depend on spatial surfaces Σ. These observables are given holographically by the area of a certain bulk spatial surface Γ ending on Σ. At finite charge density it is natural to consider the electric flux ..."
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Nonlocal order parameters for deconfinement, such as the entanglement entropy and Wilson loops, depend on spatial surfaces Σ. These observables are given holographically by the area of a certain bulk spatial surface Γ ending on Σ. At finite charge density it is natural to consider the electric flux through the bulk surface Γ in addition to its area. We show that this flux provides a refined order parameter that can distinguish ‘fractionalized ’ phases, with charged horizons, from what we term ‘cohesive ’ phases, with charged matter in the bulk. Fractionalization leads to a volume law for the flux through the surface, the flux for deconfined but cohesive phases is between a boundary and a volume law, while finite density confined phases have vanishing flux through the surface. We suggest two possible field theoretical interpretations for this order parameter. The first is as information extracted from the large N reduced density matrix associated to Σ. The second is as surface operators dual to polarized bulk ‘Dbranes’, carrying an electric dipole moment. ar