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.

Excited states of holographic superconductors from massive gravity

In this paper,we generalize the study of the model of holographic superconductors in excited states to the framework of massive gravity at the probe limit.By taking into account the effect of a massive graviton,we numerically present a family of solutions for holographic superconductors in excited states and find that the critical temperatures can be higher due to the effect of the massive graviton,in comparison with the superconductor in Einstein gravity.We also investigate the condensates and conductivities in the ground state and the excited states by studying various parameters that determine the framework of gravity background.

Holographic Schwinger effect in a soft wall AdS/QCD model

We perform a potential analysis for the holographic Schwinger effect in a deformed AdS5 model with conformal invariance broken by a background dilaton.We evaluated the static potential by analyzing the classical action of a string attached to a rectangular Wilson loop on a probe D3 brane located at an intermediate position in the bulk AdS space.We observed that the inclusion of the chemical potential tends to enhance the production rate,which is opposite to the effect of the confining scale.In addition,we calculated the critical electric field based on the Dirac-Born-Infeld(DBI)action.

五维Gauss-Bonnet纯时空下全息纠缠熵解析约束方程

引力/规范场论对偶作为研究黑洞以及量子引力性质的一种有力工具,其各种修正模式也得到越来越多的研究.Gauss-Bonnet修正描述了量子或者弦效应对时空本身的高阶曲率修正,对理解量子引力具有重要作用.由于其度规的复杂性,研究Gauss-Bonnet时空与规范场论对偶时,一般采用数值计算的方法得到全息纠缠熵的一些性质,利用反德西特时空/共形场论(AdS/CFT)对偶理论推导了五维Gauss-Bonnet纯时空下全息纠缠熵所对应的极值面应该满足的解析约束方程,为更进一步推导Gauss-Bonnet黑洞时空下全息纠缠熵的解析演化提供了新的基础.

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 insulator/superconductor phase transitions with excited states

We construct a family of solutions of the holographic insulator/superconductor phase transitions with the excited states in the AdS soliton background by using both the numerical and analytical methods. The interesting point is that the improved SturmLiouville method can not only analytically investigate the properties of the phase transition with the excited states, but also the distributions of the condensed fields in the vicinity of the critical point. We observe that, regardless of the type of the holographic model, the excited state has a higher critical chemical potential than the corresponding ground state, and the difference of the dimensionless critical chemical potential between the consecutive states is around 2.4, which is different from the finding of the metal/superconductor phase transition in the Ad S black hole background. Furthermore, near the critical point, we find that the phase transition of the systems is of the second order and a linear relationship exists between the charge density and chemical potential for all the excited states in both s-wave and p-wave insulator/superconductor models.

Lifshitz引力中的全息p波超导体

在探子极限下,通过数值方法研究了Lifshitz参数z对超导体相变的影响。具体来说,把带质量的麦克斯韦复矢量场耦合到4维Lifshitz黑洞中构造了p波超导体。发现时空各向异性程度的增加抑制导体/超导体相变和电导率。在临界温度附近,系统经历二阶相变,与平均场论结果一致。在一定程度上,此复矢量场模型是SU(2)Yang-Mills模型带一般质量的推广。

掺杂全息费米系统

构建了包括两个规范场和一个中性标量场的两流体模型.数值得到渐近标量毛AdS黑膜解.模型导入了两个可调节的化学势,从而导入了可控的掺杂参数.研究了特定参数下全息费米系统的性质.研究表明随着赝标量汤川秀树耦合增大,能隙打开,标志着系统衍生出绝缘相.固定赝标量汤川秀树耦合,随着掺杂参数的增大,能隙打开的临界值减少,能隙的形成更容易.并给出了相应的温度-掺杂相图.最后,根据模型参数,将模型分类.

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.

带有高阶修正的全息p波超导体相变

在探子极限下,通过数值方法研究了高阶修正对超导体相变的影响。具体来说,把带质量的麦克斯韦复矢量场和Weyl张量平方修正项耦合到4维AdS黑洞中构造了带有高阶修正的p波超导体模型。结果表明在比较宽的高阶参数范围内仍然可以得到比较合理的超导凝聚行为。在最低朗道能级,磁场可以诱导超导相变,且高阶修正抑制相变。然而,在激发态能级,磁场破坏超导相变,且高阶修正促进相变。

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.

The holographic fermions dual to massive gravity

We investigate the properties of the spectral function of the fermionic operator in the field theory which is dual to a 4-dimensional massive gravity. We first study the Fermi surface and the dispersion relation in the dual boundary theory. We find that as the massive parameters is decreased, the Fermi momentum becomes lower and the low energy excitation near Fermi surface behaves more like non-Fermi liquid. Then, we introduce a dipole coupling in the bulk theory and explore the emergence of a gap in the fermionic spectral function. It is found that larger critical dipole coupling is needed to open the gap than that in Einstein gravity. Accordingly,in the field theory dual to massive gravity, it requires stronger negative dipole coupling to generate the marginal Fermi liquid.

K-theoretic classification of fermionic operator mixings in holographic conformal field theories

In this paper, we apply the K-theory scheme of classifying the topological insulators/superconductors to classify the topological classes of the massive multi-flavor fermions in anti-de Sitter(Ad S) space. In the context of Ad S/conformal field theory(CFT) correspondence, the multi-flavor fermionic mass matrix is dual to the pattern of operator mixing in the boundary CFT. Thus, our results classify the possible patterns of operator mixings among fermionic operators in the holographic CFT.

全息p波超导相变的磁效应和高阶修正效应

在探子极限下,通过解析方法研究了超导体相变的磁效应和高阶修正效应。具体来说,我们把带质量的麦克斯韦复矢量场耦合到4维AdS黑洞中,构造了全息p波导体/超导体相变。首先,通过扰动方法得到了表征磁效应的多普勒解,进而对多普勒解叠加得到不同形状的涡流格点。其次,在最低朗道能级下,磁场促进相变,高阶修正抑制相变。在激发态能级下,磁场和高阶修正对超导相变的影响与最低能态下情况相反。并且,解析结果与已有的数值结果定性一致。

Two-gluon and trigluon glueballs from dynamical holography QCD

We study the scalar, vector and tensor two-gluon and trigluon glueball spectra in the framework of the 5-dimension dynamical holographic QCD model, where the metric structure is deformed self-consistently by the dilaton field. For comparison, the glueball spectra are also calculated in the hard-wall and soft-wall holographic QCD models. In order to distinguish glueballs with even and odd parities, we introduce a positive and negative coupling between the dilaton field and glueballs, and for higher spin glueballs, we introduce a deformed 5-dimension mass. With this set-up, there is only one free parameter from the quadratic dilaton profile in the dynamical holographic QCD model, which is fixed by the scalar glueball spectra. It is found that the two-gluon glueball spectra produced in the dynamical holographic QCD model are in good agreement with lattice data. Among six trigluon glueballs, the produced masses for 1±- and 2-- are in good agreement with lattice data, and the produced masses for 0--, 0＋- and 2＋- are around 1.5 GeV lighter than lattice results. This result might indicate that the three trigluon glueballs of 0--, 0＋- and 2＋- are dominated by the three-gluon condensate contribution.

Entanglement wedge cross-section with Gauss-Bonnet corrections and thermal quench

The entanglement wedge cross section(EWCS) is numerically investigated statically and dynamically in a five-dimension Ad SVaidya spacetime with Gauss-Bonnet(GB) corrections, focusing on two identical rectangular strips on the boundary. In the static case, EWCS increases as the GB coupling constant α increases and disentangles at small separation between two strips for smaller α. For the dynamic case, such a monotonic relationship between EWCS and α holds but the two strips no longer disentangle monotonically as in the static case. In the early thermal quenching stage, the disentanglement occurs at smaller αwith larger separations. Two strips then disentangle at larger separation with larger α as time evolves. Our results indicate that the higher-order derivative corrections, like the entanglement measure in the dual boundary theory, also have nontrivial effects on the EWCS evolution.