Holographic Insulator/Superconductor Phase Transition in Born–Infeld Electrodynamics

We study holographic insulator/superconductor phase transition in the framework of Born–Infeld electrodynamics both numerically and analytically. First we numerically study the efects of the Born–Infeld electrodynamics on the phase transition, find that when the Born–Infeld parameter increases, the critical chemical potential keeps invariant but the gap frequency becomes larger. Then we employ the variational method for the Sturm–Liouville eigenvalue problem to study the phase transition analytically. The analytical results obtained are found to be consistent with the numerical results.     

Holographic Insulator/Superconductor Phase Transition in Born-Infeld Electrodynamics

We study holographic insulator/superconductor phase transition in the framework of Born-Infeld electrodynamics both numerically and analytically. First we numerically study the effects of the Born-Infeld electrodynamics on the phase transition, find that when the Born-Infeld parameter increases, the critical chemical potential keeps invariant but the gap frequency becomes larger. Then we employ the variational method for the Sturm-Liouville eigenvalue problem to study the phase transition analytically. The analytical results obtained are found to be consistent with the numerical results.     

Gauge/string duality in confining theories

This is the content of a set of lectures given at the “XIII Jorge André Swieca Summer School on Particles and Fields”, Campos do Jordão, Brazil in January 2005. They intend to be a basic introduction to the topic of gauge/gravity duality in confining theories. We start by reviewing some key aspects of the low energy physics of non‐Abelian gauge theories. Then, we present the basics of the AdS/CFT correspondence and its extension both to gauge theories in different spacetime dimensions with sixteen supercharges and to more realistic situations with less supersymmetry. We discuss the different options of interest: placing D–branes at singularities and wrapping D–branes in calibrated cycles of special holonomy manifolds. We finally present an outline of a number of non‐perturbative phenomena in non‐Abelian gauge theories as seen from supergravity.     

中性top介子与轻子味破坏衰变过程

在顶色辅助的人工色(TC2)模型框架下, 研究了中性top介子π0t对轻子味破坏(LFV)过程li→ljγ,li→ljlkll和t→clilj的贡献. 考虑到当前μ→eγ过程的实验上限对TC2模型中自由参数的一些限制, 进一步计算了top介子对过程li→ljlkll和t→clilj分支比的量子修正.数值结果表明,在大部分参数空间内分支比的值可提高几个量级. top介子对某些过程的修正效应也许可被将来的实验观测到.     

Lorentz Violation and Topologically Trapped Fermions in 2+1 Dimensions

The full spectrum of two‐dimensional fermion states in a scalar soliton trap with a Lorentz breaking background is investigated in the context of graphene, where the Lorentz symmetry should not be strictly valid. The field theoretical model with Lorentz breaking terms represents Dirac electrons in one valley and in a scalar field background. The Lorentz violation comes from the difference between the Dirac electron and scalar mode velocities, which should be expected when modelling the electronic and lattice excitations in graphene. Here, only one Lorentz‐violating parameter is considered, belonging to the scalar sector. The analytical methods developed in the context of 1+1 field theories are extended to explore the effect of the Lorentz symmetry breaking in the charge carrier density of two‐dimensional materials in the presence of a domain wall with a kink profile. The width and the depth of the trapping potential from the kink is controlled by the Lorentz violating term, which is reflected analytically in the band structure and properties of the trapped states. These findings enlarge previous studies of the edge states obtained with domain wall and in strained graphene nanoribbon in a chiral gauge theory.     

黎曼面上的温度对偶性与亏格数g=1和2的弦宇宙学解

考察了一个在引力场g_μv和dilaton场背景下的有限温度玻色弦模型,导出了高亏格黎曼面上能量动量张量满足的对偶关系式;同时,还在四维Robertson–Walker(R–W)度规下证明了弦气体物质作用量的温度对偶不变性,获得了亏格数g=1和2的弦宇宙学解,并研究了运动方程的温度变换性质.     

On the algebraic curves for circular and folded strings in AdS5×S5

There have been recent advances in the construction of algebraic curves for certain classes of string solutions in the context of the AdS/CFT correspondence. In this paper we obtain the Lax operators and associated spectral curves for circular and folded string solutions in AdS ${}_5\times S^5$. In addition, we provide an original approach for the reconstruction of string solutions in S³ from their corresponding curves.     

Hyperscaling Inequalities for the Contact Process and Oriented Percolation

The contact process and oriented percolation are expected to exhibit the same critical behavior in any dimension. Above their upper critical dimension d _c, they exhibit the same critical behavior as the branching process. Assuming existence of the critical exponents, we prove a pair of hyperscaling inequalities which, together with the results of refs. 16 and 18, implies d _c=4.     

Magnetic Field Instability Driven by Anomalous Magnetic Moments of Massive Fermions and the Electroweak Interaction with Background Matter

A reversible thermotropic phase transition in an adsorption melissic acid film at the interface between n-hexane and an aqueous solution of potassium hydroxide (pH ≈ 10) is investigated by X-ray reflectometry and diffuse scattering using synchrotron radiation. The experimental data indicate that the interface “freezing” transition is accompanied not only by the crystallization of the Gibbs monolayer but also by the formation of a planar smectic structure in the ~300-Å-thick adsorption film; this structure is formed by ~50-Å-thick layers.     

类矢标准模型中规范相互作用与引力的统一

提出在无轻子的超对称类矢标准模型中,在规范作用双圈修正和引力单圈弦修正下,研究规范耦合和引力之间的统一问题.结果表明,需要两个中间质量标度.其中低质量标度在未来实验室可到达的范围内,高的质量标度约为10¹⁶GeV.     

Collective Diffusion and Strange-Metal Transport

We study a particular combination of charge and heat currents, which is decoupled with the heat current. The "heat-decoupled" (HD) current can be transported by diffusion at long distances, when the thermoelectric effect is small, large, or balanced. Using holographic models with momentum relaxation, we illustrate that the different thermoelectric effects correspond to the high temperatures and strong disorder, low temperatures, or special critical index. Meanwhile, the Einstein-like relation and the diffusion/chaos relation may be emergent. Assuming that the existence and features of HD modes appear in strange metals, we can predict that when the thermoelectric effect is not very large, the scaling of resistivity is predominantly controlled by the HD susceptibility and chaos; otherwise more physics is required.     

Fermions with cubic and quartic spectrum

We study exotic fermions with spectrum E ² ∝ p ^2N . Such spectrum emerges in the vicinity of the Fermi point with multiple topological charge N, if special symmetry is obeyed. When this symmetry is violated, the multiple Fermi point typically splits into N elementary Fermi points, i.e., Dirac points with N = 1 and spectrum E ² ∝ p ².     

Fermions and the Kaluza-Klein monopole

This paper investigates the behavior of light charged matter in the presence of the recently constructed Kaluza-Klein monopole, starting with a mechanism for obtaining such matter in the first place. For scalars the separation of variables is identical to that for the ordinary Dirac monopole, but the geometrical picture sheds some light on the strange quantum numbers of the resulting states. Fer fermions there is a new repulsive potential, even in the lowest partial wave. This renders the hamiltonian self-adjoint without any family of extensions, in contrast to the Dirac pole. Consideration of quantum effects on long-distance physics, however, modifies the basic monopole solution and restores the usual fermion physics.     

Playing with Numbers, with Fermions and Bosons

We construct nonlinear maps which realize the fermionization of bosons and the bosonization of fermions with the view of obtaining states coding naturally integers in standard or in binary basis. Specifically, with reference to spin systems, we derive raising and lowering bosonic operators in terms of standard fermionic operators and vice versa. The crucial role of multiboson operators in the whole construction is emphasized. Dedicated to Giuseppe Castagnoli for his 65th birthday.     

Dijkgraaf–Vafa Matrix Models and Integrable Systems

We review the Dijkgraaf-Vafa correspondence and give some mathematical details of the associated matrix contour integrals, before discussing recent work relating supersymmetric vacua to integrable systems.     

Note on surface growth approach for bulk reconstruction

In this paper, we show using several examples that the bulk geometry of asymptotically AdS\begin{document}$ _3 $\end{document}spacetimes can be effectively reconstructed using an intuitive and visual method called the surface growth scheme. This new approach for bulk reconstruction was originally proposed in a recent paper, along with its explicit realization using the one-shot entanglement distillation tensor network and the surface/state correspondence. In this paper, we directly analyze the growth of the bulk minimal surfaces to implement this scheme. Our study provides further support for the surface growth approach in entanglement wedge reconstruction.     

关于费米子玻色化技术的注记

传统根据Jordon和Wigner理论,构造了费米子玻色化方案.讨论证明了这种方案只在k≠k′时才成立,而在k=k′时则不成立,从而说明了费米子的玻色化技术是不完备的.     

The dynamical holographic QCD method for hadron physics and QCD matter

In this paper we present a short overview on the dynamical holographic QCD (DhQCD) method for hadron physics and QCD matter. The five-dimensional DhQCD model is constructed in the graviton-dilaton-scalar framework with the dilaton background field Φ and the scalar field X dual to the gluon condensate and the chiral condensate operator thus can represent the gluodynamics (linear confinement) and chiral dynamics (chiral symmetry breaking), respectively. The dilaton background field and the scalar field are a function of the 5th dimension, which plays the role of the energy scale, in this way, the DhQCD model can resemble the renormalization group from ultraviolet (UV) to infrared (IR). By solving the Einstein equation, the metric structure at IR is automatically deformed by the nonperturbative gluon condensation and chiral condensation in the vacuum. We review the results on the hadron spectra including the glueball spectra, the light/heavy meson spectra, as well as on QCD phase transitions, and thermodynamical as well as transport properties in the framework of the DhQCD model.