Holographic fermions with running chemical potential and dipole coupling

We explore the properties of the holographic fermions in extremal R-charged black hole background with a running chemical potential, as well as the dipole coupling between fermions and the gauge field in the bulk. We find that although the running chemical potential effect the location of the Fermi surface, it does not change the type of fermions. We also study the onset of the Fermi gap and the gap effected by running chemical potential and the dipole coupling. The spectral function in the limit ω→0$\omega \to 0$ and the existence of the Fermi liquid are also investigated. The running chemical potential and the dipole coupling altogether can make a non-Fermi liquid become the Landau–Fermi type.     

Holographic superconductors in the AdS black-hole spacetime with a global monopole

We study holographic superconductors in the Schwarzschild–AdS black hole with a global monopole through a charged complex scalar field. We calculate the condensates of the charged operators in the dual conformal field theories (CFTs) and discuss the effects of the global monopole on the condensation formation. Moreover, we compute the electric conductive using the probe approximation and find that the properties of the conductive are quite similar to those in the Schwarzschild–AdS black hole. These results can help us know more about holographic superconductors in the asymptotic AdS black holes.     

一类新的Stückelberg全息超导模型

本文研究了含Stückelberg机理的黑洞全息超导模型. 通过选取标量场新的高阶修正形式, 建立了新的Stückelberg黑洞全息超导模型. 通过研究模型参数对标量场凝聚的影响, 发现了当模型参数大于临界值时, 高阶修正可以引起一阶相变. 同时本文还考查了反作用对临界值的影响.     

Stckelberg Holographic Superconductor Models with Backreactions

We study the Stckelberg holographic superconductors away from the probe limit.We find that the backreaction of the spacetime can bring richer physics in the phase transition.Moreover we observe that the ratio ωg/Tc changes with the strength of the backreaction and is not a universal constant.     

Holographic superconductor developed in BTZ black hole background with backreactions

We develop a holographic superconductor in BTZ black hole background with backreactions. We investigate the influence of the backreaction on the condensation of the scalar hair and the dynamics of perturbation in the background spacetime. When the Breitenlohner-Freedman bound is approached, we argue that only one of two possible operators can reflect the real property of the condensation in the holographic superconductor. This argument is supported by the investigation in dynamics.     

Holographic p-wave superfluid with Weyl corrections

In this work,we study the effects of the Weyl corrections on the p-wave superfluid phase transition in terms of an EinsteinMaxwell theory coupled to a complex vector field.In the probe limit,it is observed that the phase structure is significantly modified owing to the presence of the higher order Weyl corrections.The latter,in general,facilitates the emergence of the superfluid phase as the condensate increases with the Weyl coupling measured byγ.Moreover,several features about the phase structure of the holographic superfluid are carefully investigated.In a specific region,the phase transition from the normal phase to the superfluid phase is identified to be the first order,instead of being the second order,as in the cases for many holographic superconductors.By carrying out a numerical scan of model parameters,the boundary dividing these two types of transitions is located and shown to be rather sensitive to the strength of Weyl coupling.Also,a feature known as"Cave of Winds",associated with the emergence of a second superfluid phase,is observed for specific choices of model parameters.However,it becomes less prominent and eventually disappears asγincreases.Furthermore,for temperature in the vicinity of the critical one for vanishing superfluid velocity,denoted by T0,the supercurrent is found to be independent of the Weyl coupling.The calculated ratio,of the condensate with vanishing superfluid velocity to that with maximal superfluid velocity,is in good agreement with that predicted by Ginzburg-Landau theory.While compared with the impact on the phase structure owing to the higher curvature corrections,the findings in our present study demonstrate entirely different characteristics.Further implications are discussed.     

Holographic p-Wave Superconductors in Quintessence AdS Black Hole Spacetime

We construct a holographic p-wave superconductor model in the background of quintessence AdS black hole with an SU(2)Yang–Mills gauge field and then probe the efects of quintessence on the holographic p-wave superconductor.We investigate the relation between the critical temperature and the state parameter of quintessence,and present the numerical results for electric conductivity.It is shown that the condensation of the vector field becomes harder as the absolute value of the state parameter increases.Unlike the scalar condensate in the s-wave model,the condensation of the vector field in p-wave model can occur in the total value range of the state parameter wq of quintessence.These results could help us know more about holographic superconductor and dark energy.     

Holographic Fermi arcs and a d-wave gap

We study fermion correlators in a holographic superfluid with a d-wave (spin two) order parameter. We find that, with a suitable bulk Majorana coupling, the Fermi surface is anisotropically gapped. At low temperatures the gap shrinks to four nodal points. At high temperatures the Fermi surface is partially gapped generating four Fermi arcs.     

p-Wave superconductors in D-brane systems

In this work we take the intersecting D-brane models to explore some properties of p-wave superconductor at strong coupling. Our studies are focused on four-dimensional spacetime, which is not completely researched as in planar case. Optimistically, the AdS/CFT approach to superconductor, or more precisely superconducting-like phase transition, can give us some intuitions about mysterious high _Tc$T_c$ superconductors. Concretely, we use defect D4/D6 and D4/D4 (noncritical) models to carry out comparative investigations. To make the system in the finite temperature bath, we assume that the superconducting phase is in the deconfined and chiral symmetry restoring phase for black D4-brane geometry. For the background fields, we use both analytical and numerical methods to solve the coupled nonlinear equations of motion. Near the phase transition, both methods give the mean filed behavior for the superconducting condensate. We then study gauge field perturbations of the systems to probe the AC conductivity. Similar to previous results, there comes out a gap in low frequency regime and the conductivity gets exponentially small as the condensation is enhanced. In contrast to previous investigations, we also compute the AC conductivity along the x direction, which needs to study a coupled sets of fluctuation modes. This shows us the anisotropic feature of p-wave superconductors.     

General holographic superconductor models with Gauss–Bonnet corrections

We study general models for holographic superconductors in Einstein–Gauss–Bonnet gravity. We find that different values of Gauss–Bonnet correction term and model parameters can determine the order of phase transitions and critical exponents of second-order phase transitions. Moreover we find that the size and strength of the conductivity coherence peak can be controlled. The ratios ωg/Tc${\omega }_g/Tc$ for various model parameters have also been examined.     

Holographic p-Wave Superconductors in Quintessence AdS Black Hole Spacetime

We construct a holographic p-wave superconductor model in the background of quintessence AdS black hole with an SU(2) Yang-Mills gauge field and then probe the effects of quintessence on the holographic p-wave superconductor. We investigate the relation between the critical temperature and the state parameter of quintessence, and present the numerical results for electric conductivity. It is shown that the condensation of the vector field becomes harder as the absolute value of the state parameter increases. Unlike the scalar condensate in the s-wave model, the condensation of the vector field in p-wave model can occur in the total value range of the state parameter w_q of quintessence. These results could help us know more about holographic superconductor and dark energy.     

Vortex and droplet in holographic D-wave superconductors

We investigate non-trivial localized solutions of the condensate in a (2+1$2+1$)-dimensional D-wave holographic superconductor model in the presence of a background magnetic field. The calculation is done in the context of the (3+1$3+1$)-dimensional dual gravity theory of a charged massive spin-2 field in an AdS black hole background. By using numeric techniques, we find both vortex and droplet solutions. These solutions are important for studying the full phase diagram of D-wave superconductors.     

Holographic Duals of Quark Gluon Plasmas with Unquenched Flavors

We review the construction of gravitational solutions holographically dual to N=1 quiver gauge theories with dynamical flavor multiplets.We focus on the D3-D7 construction and consider the finite temperature,finite quark chemical potential case where there is a charged black hole in the dual solution.Discussed physical outputs of the model include its thermodynamics (with susceptibilities) and general hydrodynamic properties.     

Logarithmic corrections to entropy and AdS/CFT

We calculate the correction to the Bekenstein-Hawking entropy formula for five-dimensional AdS-Schwarzschild black holes due to thermodynamic fluctuations. The result is then compared with the boundary gauge theory entropy corrections via AdS/CFT correspondence.     

A Note on Black Holes in Asymptotically Lifshitz Spacetime

We investigate several aspects of exact black hole solutions in asymptotically Lifshitz spacetime. Firstly,we calculate the tidal forces and find that in the near horizon region of such black hole backgrounds, the tidal forces diverge in the near extremal limit. Secondly, we evaluate the Wilson loops in both extremal and finite temperature cases. Finally, we obtain the corresponding shear viscosity and square of the sound speed and find that the ratio of shear viscosity to entropy density takes the universal value 1/4π in arbitrary dimensions while the square of the speed of sound saturates the conjectured bound 1/3 in five dimensions.     

On EVH black hole solution in heterotic string theory

We study the near horizon geometry of charged rotating black holes in toroidal compactifications of heterotic string theory. We analyze the extremal vanishing horizon (EVH) limit for these black hole solutions and we will show that the near horizon geometry develops an AdS₃ throat. Furthermore, we will show that the near horizon limit of near EVH black holes has a BTZ factor. We also comment on the CFT dual to this near horizon geometry.     

Astrobiology: a respectable new science

Holographic quantum chromodynamics (QCD) is an extra-dimensional approach to modelling hadrons, the bound states of the strong interactions. In holographic models, the extra spatial dimension creates a waveguide for fields, and the discrete towers of modes propagating in that waveguide are interpreted as hadronic resonances. These models are motivated by the AdS/CFT correspondence, which is a duality that relates theories in different numbers of spatial dimensions. Holographic models have the potential to provide a better understanding of strongly interacting systems of quarks and gluons, as well as unconventional superconductors and other nonperturbative systems.     

Note on the holographic c‐function

We discuss the holographic c‐function and describe an algorithm for the practical computation of the changing central charge in arbitrary RG‐flows. The conclusions are drawn from studying a particular example, which is worked out in detail. The renormalisation procedure of hep‐th/0112150 necessary to obtain the central charge is reviewed.