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29 papers found.
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Holographic self-tuning of the cosmological constant

We propose a brane-world setup based on gauge/gravity duality in which the four-dimensional cosmological constant is set to zero by a dynamical self-adjustment mechanism. The bulk contains Einstein gravity and a scalar field. We study holographic RG flow solutions, with the standard model brane separating an infinite volume UV region and an IR region of finite volume. For generic ...

Hyperscaling-violating Lifshitz hydrodynamics from black-holes: part II

The derivation of Lifshitz-invariant hydrodynamics from holography, presented in [1] is generalized to arbitrary hyperscaling violating Lifshitz scaling theories with an unbroken U(1) symmetry. The hydrodynamics emerging is non-relativistic with scalar “forcing”. By a redefinition of the pressure it becomes standard non-relativistic hydrodynamics in the presence of specific ...

Holographic photon production in heavy ion collisions

The thermal-photon emission from strongly coupled gauge theories at finite temperature is calculated using holographic models for QCD in the Veneziano limit (V-QCD). The emission rates are then embedded in hydrodynamic simulations combined with prompt photons from hard scattering and the thermal photons from hadron gas to analyze the spectra and anisotropic flow of direct photons ...

Higher derivative corrections to incoherent metallic transport in holography

Transport in strongly-disordered, metallic systems is governed by diffusive processes. Based on quantum mechanics, it has been conjectured that these diffusivities obey a lower bound D/v 2 ≳ ℏ/k B T , the saturation of which provides a mechanism for the T-linear resistivity of bad metals. This bound features a characteristic velocity v, which was later argued to be the butterfly ...

Holographic competition of phases and superconductivity

We use a holographic theory to model and study the competition of four phases: an antiferromagnetic phase, a superconducting phase, a metallic phase and a striped phase, using as control parameters temperature and a doping-like parameter. We analyse the various instabilities and determine the possible phases. One class of phase diagrams, that we analyse in detail, is similar to ...

Charge-hyperscaling violating Lifshitz hydrodynamics from black-holes

Non-equilibrium black hole horizons are considered in scaling theories with generic Lifshitz invariance and an unbroken U(1) symmetry. There is also charge-hyperscaling violation associated with a non-trivial conduction exponent. The boundary stress tensor is computed and renormalized and the associated hydrodynamic equations derived. Upon a non-trivial redefinition of boundary ...

On holographic insulators and supersolids

We obtain holographic realizations for systems that have strong similarities to Mott insulators and supersolids, after examining the ground states of Einstein-Maxwell-scalar systems. The real part of the AC conductivity has a hard gap and a discrete spectrum only. We add momentum dissipation to resolve the δ-function in the conductivity due to translational invariance. We develop ...

Effective holographic theories of momentum relaxation and violation of conductivity bound

We generalize current holographic models with homogeneous breaking of translation symmetry by incorporating higher derivative couplings, in the spirit of effective field theories. Focusing on charge transport, we specialize to two simple couplings between the charge and translation symmetry breaking sectors. We obtain analytical charged black brane solutions and compute their DC ...

Scaling of the holographic AC conductivity for non-Fermi liquids at criticality

The frequency dependence of the AC conductivity is studied in a holographic model of a non-fermi liquid that is amenable to both analytical and numerical computation. In the regime that dissipation dominates the DC conductivity, the AC conductivity is described well in the IR by a Drude peak despite the absence of quasiparticles. In the regime where pair-production-like processes ...

Thermalization in a holographic confining gauge theory

Time dependent perturbations of states in the holographic dual of a 3+1 dimensional confining theory are considered. The perturbations are induced by varying the coupling to the theory’s most relevant operator. The dual gravitational theory belongs to a class of Einstein-dilaton theories which exhibit a mass gap at zero temperature and a first order deconfining phase transition at ...

Field theory on Newton-Cartan backgrounds and symmetries of the Lifshitz vacuum

Holography for Lifshitz space-times corresponds to dual field theories on a fixed torsional Newton-Cartan (TNC) background. We examine the coupling of non-relativistic field theories to TNC backgrounds and uncover a novel mechanism by which a global U(1) can become local. This involves the TNC vector M μ which sources a particle number current, and which for flat NC space-time ...

On the gluonic operator effective potential in holographic Yang-Mills theory

The holographic formalism is applied to the calculation of the effective potential for the scalar glueball operator. Three different versions of this operator are defined, and for each we compute the associated effective potential and discuss its properties and scheme ambiguities. For one of them, the trace of the stress tensor, the potential is fixed by scale covariance and the ...

Lorentz violation, gravity, dissipation and holography

Elias Kiritsis 1 0 Crete Center for Theoretical Physics, Department of Physics, University of Crete , PO Box 2208, 71003 Heraklion, Greece 1 APC, Universite Paris 7 , Diderot, CNRS/IN2P3 (UMR du CNRS

Holographic metals and insulators with helical symmetry

Homogeneous, zero temperature scaling solutions with Bianchi VII spatial geometry are constructed in Einstein-Maxwell-Dilaton theory. They correspond to quantum critical saddle points with helical symmetry at finite density. Assuming AdS 5 UV asymptotics, the small frequency/(temperature) dependence of the AC/(DC) electric conductivity along the director of the helix are computed. ...

The confining trailing string

We extend the holographic trailing string picture of a heavy quark to the case of a bulk geometry dual to a confining gauge theory. We compute the classical trailing confining string solution for a static as well as a uniformly moving quark. The trailing string is infinitely extended and approaches a confining horizon, situated at a critical value of the radial coordinate, along ...

The holographic quantum effective potential at finite temperature and density

Elias Kiritsis 0 1 Vasilis Niarchos 1 0 APC, AstroParticule et Cosmologie, Universite Paris Diderot , CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite, 10, rue Alice Domon et Leonie

Heavy quarks in a magnetic field

The motion of a heavy charged quark in a magnetic field is analyzed in the vacuum of strongly coupled CFT. The motion of the quark is dissipative. It moves in spiral until it eventually comes to rest. The world-sheet geometry is locally AdS2 but has a time dependent horizon. The string profile in the static gauge extends from the boundary till a point where an embedding singularity ...

Multiplicities from black-hole formation in heavy-ion collisions

The formation of trapped surfaces in the head-on collision of shock waves in conformal and non-conformal backgrounds is investigated. The backgrounds include all interesting confining and non-confining backgrounds that may be relevant for QCD. Several transverse profiles of the shocks are investigated including distributions that fall-off as powers or exponentials. Different ways ...

Holographic models for QCD in the Veneziano limit

We construct a class of bottom-up holographic models with physics comparable to the one expected from QCD in the Veneziano limit of large N f and N c with fixed \( x = \frac{{{N_f}}}{{{N_c}}} \) The models capture the holographic dynamics of the dilaton (dual to the YM coupling) and a tachyon (dual to the chiral condensate), and are parametrized by the real parameter x, which can ...

Vector-axial vector correlators in weak electric field and the holographic dynamics of the chiral condensate

The transverse part of the vector-axial vector flavor current correlator in the presence of weak external electric field is studied using holography. The correlator is calculated using a bottom-up model proposed recently, that includes both contributions of higher string states and the non-linear dynamics of the chiral condensate. It is shown that for low momenta the result agrees ...