Brane Solutions Research Articles

Quasitopological magnetic brane coupled to nonlinear electrodynamics

In this paper, we are eager to construct a new class of (n+1)-dimensional static magnetic brane solutions in quasi-topological gravity coupled to nonlinear electrodynamics such as exponential and logarithmic forms. The solutions of this magnetic brane are horizonless and have no curvature. For \rho near r_{+}, the solution f(\rho) is dependent to the values of parameters q and n and for larger \rho, it depends on the coefficients of Love-Lock and quasi-topological gravities \lambda, \mu and c. The obtained solutions also have a conic singularity at r=0 with a deficit angle that is only dependent to the parameters q, n and \beta. We should remind that the two forms of nonlinear electrodynamics theory have similar behaviors on the obtained solutions. At last, by using the counterterm method, we obtain conserved quantities such as mass and electric charge. The value of the electric charge for this static magnetic brane is obtained zero.

Intermediate scalings for solv, nil, and SL2(R) black branes

In this work we will study black brane solutions that are not translationally invariant in the spatial directions along which it extends. Instead, we require homogeneity, which still allows points along the spatial directions to be related to each other by symmetries. We find Einstein-Maxwell black hole solutions whose near horizon geometry correspond to Solv (Bianchi $V1_{-1}$), Nil (Bianchi $II$) or $SL_2({\cal R})$ (Bianchi $VIII$). Interestingly we observe that at intermediate temperatures our solutions have an scaling regime where different spacetime directions scale differently. We also compute the DC conductivities for these charged solutions and study how they scale in this intermediate regime.

Exact holographic RG flows and the A1 \xd7 A1 Toda chain

We construct analytic solutions of Einstein gravity coupled to a dilaton field with a potential given by a sum of two exponentials, by rewriting the equations of motion in terms of an integrable Toda chain. These solutions can be interpreted as domain walls interpolating between different asymptotics, and as such they can have interesting applications in holography. In some cases, we can construct a solution which interpolates between an AdS fixed point in the UV limit and a hyperscaling violating boundary in the IR region. We also find analytic black brane solutions at finite temperature. We discuss the properties of the solutions and the interpretation in terms of RG flow.

Orientation dependence of confinement-deconfinement phase transition in anisotropic media

We study the T-μ phase diagram of anisotropic media, created in heavy-ion collisions (HIC). Such a statement of the problem is due to several indications that this media is anisotropic just after HIC. To study T-μ phase diagram we use holographic methods. To take into account the anisotropy we use an anisotropic black brane solutions for a bottom-up QCD approach in 5-dim Einstein-dilaton-two-Maxwell model constructed in our previous work. We calculate the minimal surfaces of the corresponding probing open string world-sheet in anisotropic backgrounds with various temperatures and chemical potentials. The dynamical wall (DW) locations, providing the quark confinement, depend on the orientation of the quark pairs, that gives a crossover transition between confinement/deconfinement phases in the dual gauge theory.

Probing anomalous driving

We study the effects of driving a magnetically charged black brane solution of Einstein-Maxwell-Chern-Simons theory by a time dependent electric field. From a holographic perspective, we find that placing a sample in a background magnetic field and driving the system via a parallel electric field generates a charge current which may oscillate for long periods and (or) may exhibit non-Ohmic behavior. We discuss how these two effects manifest themselves in various types of quenches and in periodic driving of the sample.

Supersymmetric AdS_5 black holes and strings from 5D N=4 gauged supergravity

We study supersymmetric AdS_3times Sigma _2 and AdS_2times Sigma _3 solutions, with Sigma _2=S^2,H^2 and Sigma _3=S^3,H^3, in five-dimensional N=4 gauged supergravity coupled to five vector multiplets. The gauge groups considered here are U(1)times SU(2)times SU(2), U(1)times SO(3,1) and U(1)times SL(3,mathbb {R}). For U(1)times SU(2)times SU(2) gauge group admitting two supersymmetric N=4AdS_5 vacua, we identify a new class of AdS_3times Sigma _2 and AdS_2times H^3 solutions preserving four supercharges. Holographic RG flows describing twisted compactifications of N=2 four-dimensional SCFTs dual to the AdS_5 vacua to the SCFTs in two and one dimensions dual to these geometries are numerically given. The solutions can also be interpreted as supersymmetric black strings and black holes in asymptotically AdS_5 spaces with near horizon geometries given by AdS_3times Sigma _2 and AdS_2times H^3, respectively. These solutions broaden previously known black brane solutions including half-supersymmetric AdS_5 black strings recently found in N=4 gauged supergravity. Similar solutions are also studied in non-compact gauge groups U(1)times SO(3,1) and U(1)times SL(3,mathbb {R}).

Rotating hairy black holes in AdS5 \xd7 S5

We present a numerical study of fully non-linear, rotating and charged hairy black hole solutions in five-dimensional anti-de Sitter space, which originate from a consistent truncation of mathcal{N}=8 supergravity, and can be consistently embedded in type IIB supergravity with AdS5×S5 asymptotics. The hairy black holes have one scalar field charged under a U(1) gauge field, and branch from the near-extremal Cvetič, Lü and Pope solutions. We give numerical evidence that the hairy solutions exist arbitrarily close to the BPS bound for all charges, and saturate it in the T → 0 and T → ∞ limits. We give further evidence for the conjecture of Markevičiūtė and Santos, that on the BPS bound, the rotating hairy black holes form a two-parameter family of solutions with finite entropy, and can be regarded as a one-parameter extension of the supersymmetric Gutowski and Reall black hole. We analyse the approach to the supersymmetric limit and explore the full phase diagram. In the planar horizon limit we find a two parameter family of rotating hairy black brane solutions which cannot be obtained via a Lorentz boost. The field theory dual exhibits a spontaneously generated current. The results of this paper suggest rich and intricate structure of hairy black hole solutions in AdS5×S5, and highlight their importance in understanding the thermodynamics of mathcal{N}=4 SYM.

Holography of electrically and magnetically charged black branes

We construct a new class of black brane solutions in Einstein-Maxwell-dilaton (EMD) theory, which is characterized by two parameters a, b. Based on the obtained solutions, we make detailed analysis on the ground state in zero temperature limit and find that for many cases it exhibits the behavior of vanishing entropy density. We also find that the linear-T resistivity can be realized in a large region of temperature for the specific case of a^2=1/3, which is the Gubser-Rocha model dual to a ground state with vanishing entropy density. Moreover, for a=1 we analytically construct the black brane which is magnetically charged by virtue of the electric-magnetic (EM) duality. Various transport coefficients are calculated and their temperature dependence are obtained in the high temperature region.

Holographic aspects of a higher curvature massive gravity

We study the holographic dual of a massive gravity with Gauss–Bonnet and cubic quasi-topological higher curvature terms. Firstly, we find the energy–momentum two point function of the 4-dimensional boundary theory where the massive term breaks the conformal symmetry as expected. An a-theorem is introduced based on the null energy condition. Then we focus on a black brane solution in this background and derive the ratio of shear viscosity to entropy density for the dual theory. It is worth mentioning that the concept of viscosity as a transport coefficient is obscure in a nontranslational invariant theory as in our case. So although we use the Green–Kubo’s formula to derive it, we rather call it the rate of entropy production per the Planckian time due to a strain. Results smoothly cover the massless limit.

Black brane solution in Rastall AdS massive gravity and viscosity bound

In this paper, we introduced the black brane solution in Rastall theory and in the context of massive gravity. The ratio of shear viscosity to entropy density is calculated for this solution. Our result shows that the KSS bound violates this theory.

Complexity and behind the horizon cut off

Motivated by Toverline{T} deformation of a conformal field theory we compute holographic complexity for a black brane solution with a cutoff using “complexity=action” proposal. In order to have a late time behavior consistent with Lloyd’s bound one is forced to have a cutoff behind the horizon whose value is fixed by the boundary cutoff. Using this result we compute holographic complexity for two dimensional AdS solutions where we get expected late times linear growth. It is in contrast with the naively computation which is done without assuming the cutoff where the complexity approaches a constant at the late time.

The emergence of flagpole and flag-dipole fermions in fluid/gravity correspondence

The emergence of flagpole and flag-dipole singular spinor fields is explored, in the context of fermionic sectors of fluid/gravity correspondence, arising from the duality between the gravitino, in supergravity, and the phonino, in supersymmetric hydrodynamics. Generalized black branes, whose particular case consists of the AdS–Schwarzschild black brane, are regarded. The correspondence between hydrodynamic transport coefficients, and the universal absorption cross sections of the generalized black branes, is extended to fermionic sectors, including supersound diffusion constants. A free parameter, in the generalized black brane solution, is shown to control the flipping between regular and singular fermionic solutions of the equations of motion for the gravitino.

Linear stability of f(R, \u03d5, X) thick branes: tensor perturbations

We explore thick branes in f (R, ϕ, X) gravity. We obtain the linear tensor perturbation equation of f (R, ϕ, X) branes and show that the branes are stable against the tensor perturbations under the condition of frac{partial fleft(R,phi, Xright)}{partial R}>0 . In order to obtain thick brane solutions of the fourth-order field equations in this theory, we employ the reconstruction technique. We get exact solutions of the specific f (R, ϕ, X) thick brane generated by a noncanonical scalar field. It is shown that the zero mode of the graviton for the thick brane is localized under certain conditions. This implies that the four-dimensional Newtonian potential is recovered on the brane. The effects of the Kaluza-Klein modes of the graviton for the f (R, ϕ, X) thick brane are also discussed.

Wilson loop calculation in QGP using non-supersymmetric AdS/CFT

Previously, two of the present authors obtained the decoupling limit and the corresponding throat geometry of non-supersymmetric D3 brane solution of type IIB string theory. In analogy with the supersymmetric case, it describes the gravity dual of a non-supersymmetric gauge theory with QCD-like properties such as running coupling and confinement (or mass gap) in certain range of its parameters. In this paper, we consider a ‘black’ version of the non-supersymmetric D3 brane solution in the decoupling limit and use this gravity background to holographically compute the expectation value of a time-like Wilson loop which, in turn, is related to the potential of a heavy quark-antiquark pair. By boosting the gravity solution along one of the brane directions and placing the pair at an arbitrary orientation with this direction, we numerically obtain the variation of the screening length as well as the potential with velocity, its orientation with respect to the direction of motion and other parameters of the theory. Remarkably enough, our results are in qualitative agreement with those obtained holographically in supersymmetric gauge theories indicating that these features are quite robust and universal as they are insensitive to the presence of any supersymmetry in the theory. The physical interpretations of the variations with respect to the other parameters of the theory, not observed in supersymmetric theory, have also been given.

Einstein\u2013Yang\u2013Mills AdS black brane solution in massive gravity and viscosity bound

We introduce the Einstein–Yang–Mills AdS black brane solution in context of massive gravity. The ratio of shear viscosity to entropy density is calculated for this solution. This value violates the KSS bound if we apply the Dirichlet boundary and regularity on the horizon conditions.

Holographic zero sound from spacetime-filling branes

We use holography to study sound modes of strongly-interacting conformal field theories with non-zero temperature, T , and U(1) chemical potential, μ. Specifically, we consider charged black brane solutions of Einstein gravity in (3+1)-dimensional Anti-de Sitter space coupled to a U(1) gauge field with Dirac-Born-Infeld action, representing a spacetime-filling brane. The brane action has two free parameters: the tension and the non-linearity parameter, which controls higher-order terms in the field strength. For all values of the tension, non-linearity parameter, and T /μ, and at sufficiently small momentum, we find sound modes with speed given by the conformal value and attenuation constant of hydrodynamic form. In particular we find sound at arbitrarily low T /μ, outside the usual hydrodynamic regime, but in the regime where a Fermi liquid exhibits Landau’s “zero” sound. In fact, the sound attenuation constant as a function of T /μ qualitatively resembles that of a Fermi liquid, including a maximum, which in a Fermi liquid signals the collisionless to hydrodynamic crossover. We also explore regimes of the tension and non-linearity parameter where two other proposed definitions of the crossover are viable, via pole collisions in Green’s functions or peak movement in the charge density spectral function.

D=10 dyonic black holes in string inspired models

We consider string inspired models in $D=10$ spacetime dimensions, which include couplings with 1- and 3-form fields as well as $R^4$ higher curvature corrections to the gravitational action. For such models, we explicitly construct a family of black hole solutions with both electric and magnetic charges, and with different horizon topologies. The solutions exhibit some features similar to those of self-gravitating monopoles in Einstein-Yang-Mills theory, which we discuss. When higher-curvature corrections are switched off, our solutions reduce to charged $p$-brane solutions previously studied in the literature. Novel qualitative features appear due to the $R^4$ terms, though. Such is the case of the emergence of branch singularities for charged solutions that, nonetheless, can be shielded by the event horizon.

Charged black strings and black branes in Lovelock theories

It is well known that the Reissner-Norstrom solution of Einstein-Maxwell theory cannot be cylindrically extended to higher dimension, as with the black hole solutions in vacuum. In this paper we show that this result is circumvented in Lovelock gravity. We prove that the theory containing only the quadratic Lovelock term, the Gauss-Bonnet term, minimally coupled to a $U(1)$ field, admits homogeneous black string and black brane solutions characterized by the mass, charge and volume of the flat directions. We also show that theories containing a single Lovelock term of order $n$ in the Lagrangian coupled to a $(p-1)$-form field admit simple oxidations only when $n$ equals $p$, giving rise to new, exact, charged black branes in higher curvature gravity. For General Relativity this stands for a Lagrangian containing the Einstein-Hilbert term coupled to a massless scalar field, and no-hair theorems in this case forbid the existence of black branes. In all these cases the field equations acquire an invariance under a global scaling scale transformation of the metric. As explicit examples we construct new magnetically charged black branes for cubic Lovelock theory coupled to a Kalb-Ramond field in dimensions $(3m+2)+q$, with $m$ and $q$ integers, and the latter denoting the number of extended flat directions. We also construct dyonic solutions in quartic Lovelock theory in dimension $(4m+2)+q$.

Heating up exotic RG flows with holography

We use holography to study finite-temperature deformations of RG flows that have exotic properties from an RG viewpoint. The holographic model consists of five-dimensional gravity coupled to a scalar field with a potential. Each negative extrema of the potential defines a dual conformal field theory. We find all the black brane solutions on the gravity side and use them to construct the thermal phase diagrams of the dual theories. We find an intricate phase structure that reflects and extends the exotic properties at zero temperature.

Spherical branes

We construct new solutions of ten-dimensional supergravity with sixteen super-charges which describe the backreaction of Dp-branes with spherical worldvolume. These solutions are holographically dual to the (p + 1)-dimensional maximally supersymmetric Yang-Mills theory on Sp+1. The finite size of the sphere provides an IR cut-off for the gauge theory which is manifested in the supergravity solution as a smooth cap-off of the geometry. In the UV the size of the sphere plays no role and the backgrounds asymptote to the well-known supergravity solutions that describe the near-horizon limit of flat Dp-branes. We compute the on-shell action of our spherical brane solutions and show that it is in agreement with recent supersymmetric localization results for the free energy of maximal SYM theory on Sp+1.