Diagnosing Fractionalization from the Spin Dynamics of Z2Z_2 Spin Liquids on the Kagome Lattice by Quantum Monte Carlo Simulations

Based on large-scale quantum Monte Carlo simulations, we examine the dynamical spin structure factor of the Balents-Fisher-Girvin kagome lattice quantum spin-$1/2$ model, which is known to harbor an extended $Z_2$ quantum spin liquid phase. We use a correlation-matrix sampling scheme combined with a stochastic analytic continuation method to resolve the spectral functions of this anisotropic quantum spin model with a three-site unit-cell. Based on this approach, we monitor the spin dynamics throughout the phase diagram of this model, from the XY-ferromagnetic region to the $Z_2$ quantum spin liquid regime. In the latter phase, we identify a gapped two-spinon continuum in the transverse scattering channel, which is faithfully modeled by an effective spinon tight-binding model. Within the longitudinal channel, we identify gapped vison excitations and exhibit indications for the translational symmetry fractionalization of the visons via an enhanced spectral periodicity.Comment: 6 pages, 9 figures, v2: published versio

Direct contour deformation with arbitrary masses in the loop

We present a method, which constructs a suitable deformation vector in loop momentum space, when the loop integration is done numerically with the help of the subtraction method. The method presented here extends previously discussed techniques from the massless case to the general case of arbitrary masses in the loop.Comment: 18 pages, version to be publishe

Direct numerical integration for multi-loop integrals

We present a method to construct a suitable contour deformation in loop momentum space for multi-loop integrals. This contour deformation can be used to perform the integration for multi-loop integrals numerically. The integration can be performed directly in loop momentum space without the introduction of Feynman or Schwinger parameters. The method can be applied to finite multi-loop integrals and to divergent multi-loop integrals with suitable subtraction terms. The algorithm extends techniques from the one-loop case to the multi-loop case. Examples at two and three loops are discussed explicitly.Comment: 20 pages, v2: version to be published, v3: acknowledgement adde

Detection and visualisation of climate trends in China

Research on climate trends in China has been carried out within a co-operation of the Justus Liebig Universities Department of Geography and Zentrum für internationale Entwicklungs- und Umweltforschung (ZEU) and the Nanjing Institute of Geography and Limnology (CAS). First results were introduced by BECKER et al. 2003 a, b who worked on precipitation trend analyses in the Yangtze River Catchment. In the meanwhile, the National Climatic Centre of China (NCCC) kindly provided climatic data in China within the framework of this co-operation. Financial support from the CAS Key project KZCX3-SW-331 and the NSFC project 40271112 enabled the data acquisition. The analysis of both, precipitation and temperature data for the whole of China from 1951- 2002 can be carried out now. A shorter version of the precipitation trend observation will soon be published in Theoretical and Applied Climatology (GEMMER et al. 2003, accepted for publication/in print). Results of the temperature trend research have not been published yet. They will be submitted to an international Journal when further statistical approaches with regard to daily temperature data are processed. The discussion paper in hand will make the actual results accessible for further research groups in Germany. --

Temporal and spatial heterogeneity in aging colloids: a mesoscopic model

A coarse-grained model of dense hard sphere colloids building on simple notions of particle mobility and spatial coherence is presented and shown to reproduce results of experiments and simulations for key quantities such as the intermediate scattering function, the particle mean-square displacement and the $\chi_{4}$ mobility correlation function. All results are explained by two emerging and interrelated dynamical properties: i) a rate of intermittent events, quakes, which decreases as the inverse of the system age t; ii) a length scale characterizing correlated domains, which increases linearly in log t. This leads to simple and accurate scaling forms expressed in terms of a single scaling variable Finally, we propose a method to experimentally extract the growing length scale of an aging colloid and suggest that a suitable scaling of the probability density function of particle displacement can experimentally reveal the rate of quakes.Comment: 5 pages 6 figure

Dynamic Switching State Systems for Visual Tracking

This work addresses the problem of how to capture the dynamics of maneuvering objects for visual tracking. Towards this end, the perspective of recursive Bayesian filters and the perspective of deep learning approaches for state estimation are considered and their functional viewpoints are brought together