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Extremal Horizons with Reduced Symmetry: Hyperscaling Violation, Stripes, and a Classification for the Homogeneous Case
- JHEP 1303 (2013) 126 [1212.1948]. – 55
"... Classifying the zero-temperature 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 anti-de Sitter asymptotics. In a recent paper [1], we propos ..."
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Cited by 15 (3 self)
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Classifying the zero-temperature 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 anti-de Sitter asymptotics. In a recent paper [1], we proposed a Bianchi classification of the extremal near-horizon 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
Holography and hydrodynamics for EMD theory with two Maxwell fields, JHEP 1303
, 2013
"... We use ‘generalized dimensional reduction ’ to relate a specific Einstein-Maxwell-Dilaton (EMD) theory, including two gauge fields, three neutral scalars and an axion, to higher-dimensional AdS gravity (with no higher-dimensional Maxwell field). In general, this is a dimensional reduction over compa ..."
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Cited by 6 (0 self)
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We use ‘generalized dimensional reduction ’ to relate a specific Einstein-Maxwell-Dilaton (EMD) theory, including two gauge fields, three neutral scalars and an axion, to higher-dimensional AdS gravity (with no higher-dimensional Maxwell field). In general, this is a dimensional reduction over compact Einstein spaces in which the dimension of the com-pact space is continued to non-integral values. Specifically, we perform a non-diagonal Kaluza-Klein (KK) reduction over a torus, involving two KK gauge fields. Our aim is to determine the holographic dictionary and hydrodynamic behaviour of the lower-dimensional theory by performing the generalized dimensional reduction on AdS. We study a specific example of a black brane carrying a wave, whose universal sector is described by gravity coupled to two Maxwell fields, three neutral scalars and an axion, and compute the first order transport coefficients of the dual theory. In these theories ζ̂s/η ̂ < 2 1/(d − 1) − ĉ2s, where ĉs is the speed of sound, violating a conjectured bound, but an alternative bound is satisfied. 1 ar
Imperial/TP/2013/JG/01 Holographic charge density waves
"... We show that strongly coupled holographic matter at finite charge density can exhibit charge density wave phases which spontaneously break trans-lation invariance while preserving time-reversal and parity invariance. We show that such phases are possible within Einstein-Maxwell-dilaton the-ory in ge ..."
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Cited by 4 (1 self)
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We show that strongly coupled holographic matter at finite charge density can exhibit charge density wave phases which spontaneously break trans-lation invariance while preserving time-reversal and parity invariance. We show that such phases are possible within Einstein-Maxwell-dilaton the-ory in general spacetime dimensions. We also discuss related spatially modulated phases when there is an additional coupling to a second vector field, possibly with non-zero mass. We discuss how these constructions, and others, should be associated with novel spatially modulated ground states. ar
Interpolating from Bianchi attractors to Lifshitz and AdS spacetimes
- JHEP
, 2014
"... Abstract: We construct classes of smooth metrics which interpolate from Bianchi attractor geometries of Types II, III, VI and IX in the IR to Lifshitz or AdS2 × S3 geometries in the UV. While we do not obtain these metrics as solutions of Einstein gravity coupled to a simple matter field theory, we ..."
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Abstract: We construct classes of smooth metrics which interpolate from Bianchi attractor geometries of Types II, III, VI and IX in the IR to Lifshitz or AdS2 × S3 geometries in the UV. While we do not obtain these metrics as solutions of Einstein gravity coupled to a simple matter field theory, we show that the matter sector stress-energy required to support these geometries (via the Einstein equations) does satisfy the weak, and therefore also the null, energy condition. Since Lifshitz or AdS2×S3 geometries can in turn be connected to AdS5 spacetime, our results show that there is no barrier, at least at the level of the energy conditions, for solutions to arise connecting these Bianchi attractor geometries to AdS5 spacetime. The asymptotic AdS5 spacetime has no non-normalizable metric deformation turned on, which suggests that furthermore, the Bianchi attractor geometries can be the IR geometries dual to field theories living in flat space, with the breaking of symmetries being either spontaneous or due to sources for other fields. Finally, we show that for a large class of flows which connect two Bianchi attractors, a C-function can be defined which is monotonically decreasing from the UV to the IR as long as the null energy condition is satisfied. However, except for special examples of Bianchi attractors (including AdS space), this function does not attain a finite and non-vanishing constant value at the end points. ar X iv
Thermodynamics and instabilities . . .
, 2013
"... We extend our analysis of a IIB supergravity solution dual to a spatially anisotropic finite-temperature N = 4 super Yang-Mills plasma. The solution is static, possesses an anisotropic horizon, and is completely regular. The full geometry can be viewed as a renormalization group flow from an AdS geo ..."
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We extend our analysis of a IIB supergravity solution dual to a spatially anisotropic finite-temperature N = 4 super Yang-Mills plasma. The solution is static, possesses an anisotropic horizon, and is completely regular. The full geometry can be viewed as a renormalization group flow from an AdS geometry in the ultraviolet to a Lifshitz-like geometry in the infrared. The anisotropy can be equivalently understood as resulting from a position-dependent θ-term or from a non-zero number density of dissolved D7-branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e. mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.
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"... Video calls in CoordCom The proposed Video Call System, suitable for use in the CoordCom G5 system, offers the ability to receive 3G video calls. It will give the call taker a much better overview of the emergency situation and help the emergency response teams to receive a more exact briefing. Regu ..."
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Video calls in CoordCom The proposed Video Call System, suitable for use in the CoordCom G5 system, offers the ability to receive 3G video calls. It will give the call taker a much better overview of the emergency situation and help the emergency response teams to receive a more exact briefing. Regular SIP phone calls will also be supported by the system, as well as seamless integration with routers and firewalls. 2 (87)
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"... Abstract: We provide a simple low energy description of recombination of intersecting D-branes using super Yang-Mills theory. The recombination is realized by condensation of an off-diagonal tachyonic fluctuation localized at the intersecting point. The recombination process is equivalent to brane-a ..."
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Abstract: We provide a simple low energy description of recombination of intersecting D-branes using super Yang-Mills theory. The recombination is realized by condensation of an off-diagonal tachyonic fluctuation localized at the intersecting point. The recombination process is equivalent to brane-antibrane annihilation, thus our result confirms Sen’s conjecture on tachyon condensation, although we work in the super Yang-Mills theory whose energy scale is much lower than α ′. We also discuss the decay width of non-parallelly separated D-branes.
