Critical line near the zero-density critical point of the Kosterlitz-Thouless transition

Using low-fugacity expansions, we study the exact behavior of the Kosterlitz-Thouless critical line near the zero-density critical point. We show that the critical temperature deviates from its zero-density value by a term proportional to the square root of the density.     

Correlation inequalities and the Kosterlitz-Thouless transition for anisotropic rotators

I give a proof of the Kosterlitz-Thouless transition for sufficiently anisotropic (J _zJ _x ^–1 =J _zJ _y ^–1 <2q ^–(JKT)^–J) two-dimensionalN-component rotators (N 3). The method is based on Wells' inequality and is related to mean field Gaussian inequalities.     

Kosterlitz-Thouless transition of the quasi-two-dimensional trapped Bose gas

We use quantum Monte Carlo methods to compute the density profile, the nonclassical moment of inertia, and the condensate fraction of an interacting quasi-two-dimensional trapped Bose gas with up to N ~ 5 x 10(5) atoms and parameters closely related to recent experiments. We locate the Kosterlitz-Thouless temperature T(KT) and discuss intrinsic signatures of the onset of superfluidity in the density profile. Below T(KT), the condensate fraction is macroscopic even for our largest systems and decays only slowly with system size. We show that the thermal population of excited states in the transverse direction changes the two-dimensional density profile noticeably in both the normal and the superfluid phase.     

Kosterlitz-Thouless phase transition in microcavity polariton system

The Kosterlitz-Thouless phase transition in a system of exciton-polaritons in a microcavity is studied. The transition temperature to superfluid state was found as a function of exciton-photon detuning. A nonquadratic dispersion law was taken into account in the framework of the self-consistent harmonic approximation (SCHA). The text was submitted by the authors in English.     

Analytic solution of the renormalization equations of the Kosterlitz-Thouless transition

The Kosterlitz-Thouless renormalization equations are shown to have an analytic solution, for the whole range of their validity. The solution enables us to express one of the previously unknown parameters used for flux-flow resistance in thin film superconductors, in term of the parameters of the Kosterlitz-Thouless transition.     

Kosterlitz-Thouless transition for 4He films adsorbed to rough surfaces

We report the study of adsorption isotherms of 4He on several well characterized rough CaF2 surfaces using a quartz crystal microbalance technique at 1.672 K. The signature of decoupled mass observed on crossing the Kosterlitz-Thouless transition as a function of 4He film thickness decreases and becomes increasingly difficult to identify as the surface roughness is increased. A peak in the dissipation, indicative of the onset of superfluidity, changes little with roughness.     

Theoretical methods in the critical region of a phase transition

In this review we survey the various experiments completed or in preparation, which are designed to probe the anomalous magnetic moment of the muon to greater and greater precision. The emphasis lies particularly on the general issues involved and also on the most recent developments.     

各向异性超导体电阻转变的修正Kosterlitz-Thouless相变模型

从二维系统的Kosterlitz-Thouless (KT) 相变理论出发，在关联长度中引入热激活能和平均钉扎高度，提出了修正的KT相变模型.该模型与库伦气体标度理论和Halperin-Nelson关系具有一致性.应用修正的KT相变模型研究磁场下Tl₂Ba₂CaCu₂O_x(Tl-2212)薄膜电阻转变的标度行为，发现由电阻转变计算得到的平均钉扎高度与温度具有线性依赖关系，实验结果支持修正的KT相变模型. 关键词： 标度行为 各向异性超导体 电阻转变     

Zero-temperature Kosterlitz-Thouless transition in a two-dimensional quantum system

We construct a local interacting quantum dimer model on the square lattice, whose zero-temperature phase diagram is characterized by a line of critical points separating two ordered phases of the valence bond crystal type. On one side, the line of critical points terminates in a quantum transition inherited from a Kosterlitz-Thouless transition in an associated classical model. We also discuss the effect of a longer-range dimer interaction that can be used to suppress the line of critical points by gradually shrinking it to a single point. Finally, we propose a way to generalize the quantum Hamiltonian to a dilute dimer model in presence of monomers and we qualitatively discuss the phase diagram.     

The Kosterlitz-Thouless phase transition in two-dimensional hierarchical Coulomb gases

Within the context of a particular statistical discrimination task, we make a quantitative comparison between the performance of a feed-forward neural network and the information-theoretic optimal performance. We also address the ability of such networks to generalize and the effect of network architecture on performance.     

Molecular-dynamics simulation of methane adsorbed on MgO: Evidence for a Kosterlitz-Thouless transition

A realistic model of a monolayer molecular crystal of methane adsorbed on the (100) surface of MgO has been studied by means of molecular dynamics. The model treates the atomicity of the MgO substrate explicitly. Large corrugations in energy are found for both the translational and rotational motion of methane across the substrate. The preferred configurations of adsorption is over an Mg²⁺ ion in a tripod-down orientation. The orientationally ordered low-energy states of the monolayer have been found. Finite-size-scaling calculations on systems of different sizes indicate, however, that the ordered state exhibits only quasi-long-range order. The disclinations in the ordered phase exist in low concentrations and in bound pairs. Evidence is presented for a Kosterlitz-Thouless-type unbinding transition occurring at T _c ≈ 27 K. No evidence is found for a first-order transition. The specific heat exhibits an anomaly at T ≈ 32 K. The disclination density in the region of the transition is reported; below T _c, this density can be fitted to an Arrhenius-type law, yielding an estimate of the core enegy for a bound vortex-antivortex pair.