Lattice calculations

In this contribution we describe how an exact chiral symmetry can be realized on the lattice. A practical realization of a lattice Dirac operator that leads to a chiral invariant lattice action is discussed and a simulation with this operator is presented that aims at testing the phenomenon of spontaneous chiral symmetry breaking in QCD.Received: 30 September 2002, Published online: 22 October 2003PACS: 11.15.Ha Lattice gauge theory - 12.38.Gc Lattice QCD calculations     

Beyond the quark model of hadrons from lattice QCD

Lattice QCD can give direct information on OZI-violating contributions to mesons. Here we explore the contributions that split flavour singlet and non-singlet meson masses. I discuss in detail the spectrum and decays for scalar mesons (i.e. including glueball effects). I also review the status of hybrid mesons and their decays.Received: 30 September 2002, Published online: 22 October 2003PACS: 12.38.Gc Lattice QCD calculations - 12.39.Mk Glueball and nonstandard multi-quark/gluon states     

基于Lattice Server中间件的束流光学参数测量

根据合肥先进光源(HALF)的需求,在合肥先进光源预研项目中,开展了Lattice Server中间件技术的应用研究,开发出Lattice Server中间件。为验证Lattice Server中间件软件结构的可行性,利用合肥光源储存环,采用Python语言开发了基于Lattice Server中间件的束流光学参数测量。测量结果表明,该Lattice Server中间件实现了加速器上层物理应用与控制系统的交互,所测束流光学参数准确,证实了Lattice Server中间件软件结构的可行性。     

Plausible arguments for a large elastic response of the fluxoid lattice

The non-local elastic behaviour of the Fluxoid Lattice in type-II superconductors, established rigorously elsewhere, may be deduced by plausible reasoning from well known properties of the Lattice.     

Symmetry Reductions and Exact Solutions of Blaszak-Marciniak Four-Field Lattice Equation

Applying the Lie group method to the differential-difference equation, the Lie point symmetry of Blaszak-Marciniak four-field Lattice equation is obtained. Using the obtained symmetry, the similarity reduction equations of Blaszak-Marciniak four-field Lattice equation are derived. Solving the reduction, we get the solution of Blaszak-Marciniak four-field Lattice equation which not only recovers one of the solutions obtained by Ma and Hu [J. Math. Phys. 40 (1999) 6071] but also has the singularity when we choose the arbitrary constants accurately.     

复杂流动的LBGK模拟

ＬＢＧＫ方法在保留了格子气模型的一些优点的同时，克服了格子气模型的不足之处．应用ＬＢＧＫ方法，可以对更复杂的流体进行模拟．本文讨论了一种九点ＬＢＧＫ模型，并用Ｃｈａｐｍａｎ－Ｅｎｓｋｏｇ展开方法和多尺度技术证明其在二阶精度上表现为标准的Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程．用该模型对圆柱绕流和管排流动进行模拟的结果显示，该模型能较好地模拟复杂流动现象，并具有一定工程应用背景．     

Application of Lattice Boltzmann Method to sensitivity analysis via complex differentiation

Sensitivity analysis of flows computed by Lattice Boltzmann Method via Complex Differentiation is proposed. The theoretical work is illustrated and the proposed method assessed considering the D2Q9 scheme, along with the differentiation of the Lattice Boltzmann Equation. Boundary condition implementation is also detailed. Some examples illustrate the capability of the proposed method.     

Shear modulus and compliance in the range of the dynamic glass transition for metallic glasses

High-resolution synchrotron-radiation powder diffraction experiments were performed to observe structural changes induced by hydrogen loading in rapidly-quenched Ti-Zr-Ni alloy ribbons with dominant icosahedral character. Lattice expansion effects due to hydrogen storage in Ti-Zr-Ni quasicrystals as well as phonon and phason disorder coefficients are obtained from an analysis of diffraction linewidths. Received: 26 August 1997 / Revised: 8 January 1998 / Accepted: 10 February 1998     

Thermal expansion of InBi

Linear thermal expansion of InBi single crystal has been measured between ?186 and 100°C. Lattice constant a shows a normal behaviour over the measured temperature range. Lattice constant c, however, contracts monotonically with increasing temperature in this range.     

Application of Rational Expansion Method for Differential-Difference Equation

In this paper, we applied the rational formal expansion method to construct a series of soliton-like and period-form solutions for nonlinear differential-difference equations. Compared with most existing methods, the proposed method not only recovers some known solutions, but also finds some new and more general solutions. The efficiency of the method can be demonstrated on Toda Lattice and Ablowitz-Ladik Lattice.     

Phenomenological renormalization group approach to the anisotropic two-layer Ising model

The anisotropic two-layer Ising model is studied by the phenomenological renormalization group method. It is found that the anisotropic two-layer Ising model with symmetric couplings belongs to the same universality class as the two dimensional Ising model.Received: 2 March 2003, Published online: 11 August 2003PACS: 05.50.+q Lattice theory and statistics (Ising, Potts, etc.) - 02.70.-c Computational techniques     

A lattice Boltzmann method for incompressible two-phase flows on partial wetting surface with large density ratio

This paper reports a new numerical scheme of the lattice Boltzmann method for calculating liquid droplet behaviour on particle wetting surfaces typically for the system of liquid–gas of a large density ratio. The method combines the existing models of Inamuro et al. [T. Inamuro, T. Ogata, S. Tajima, N. Konishi, A lattice Boltzmann method for incompressible two-phase flows with large density differences, J. Comput. Phys. 198 (2004) 628–644] and Briant et al. [A.J. Briant, P. Papatzacos, J.M. Yeomans, Lattice Boltzmann simulations of contact line motion in a liquid–gas system, Philos. Trans. Roy. Soc. London A 360 (2002) 485–495; A.J. Briant, A.J. Wagner, J.M. Yeomans, Lattice Boltzmann simulations of contact line motion: I. Liquid–gas systems. Phys. Rev. E 69 (2004) 031602; A.J. Briant, J.M. Yeomans, Lattice Boltzmann simulations of contact line motion: II. Binary fluids, Phys. Rev. E 69 (2004) 031603] and has developed novel treatment for partial wetting boundaries which involve droplets spreading on a hydrophobic surface combined with the surface of relative low contact angles and strips of relative high contact angles. The interaction between the fluid–fluid interface and the partial wetting wall has been typically considered. Applying the current method, the dynamics of liquid drops on uniform and heterogeneous wetting walls are simulated numerically. The results of the simulation agree well with those of theoretical prediction and show that the present LBM can be used as a reliable way to study fluidic control on heterogeneous surfaces and other wetting related subjects.     

Study of spin sum rules （and the strong coupling constant at large distances）

We present recent results from Jefferson Lab on sum rules related to the spin structure of the nucleon. We then discuss how the Bjorken sum rule with its connection to the Gerasimov-Drell-Hearn sum, allows us to conveniently define an effective coupling for the strong force at all distances.     

Entropy Function Approach to the Lattice Boltzmann Method

In this paper, we present the construction of the Lattice Boltzmann method equipped with the H-theorem. Based on entropy functions whose local equilibria are suitable to recover the Navier–Stokes equations in the framework of the Lattice Boltzmann method, we derive a collision integral which enables simple identification of transport coefficients, and which circumvents construction of the equilibrium. We discuss performance of this approach as compared to the standard realizations.     

Chiral symmetry and lattice QCD

Four lectures about chiral symmetry and dynamical fermions in QCD. 1) Chiral symmetry in continuum QCD with an eye toward lattice simulations. 2) Lattice fermions with exact chiral symmetry: staggered fermions, fermions in five dimensions, chiral fermions in four dimensions. 3) A typical lattice simulation from beginning to end: the simulation algorithm, designing observables to measure some desired quantity, analyzing the data. 4) Recent lattice results relevant to chiral symmetry: a mini-review.     

Latest lattice results for baryon spectroscopy

Theoretical and computational advances have enabled not only the masses of the ground states,but also some of the low-lying excited states to be calculated using Lattice Gauge Theory.In this talk,I look at recent progress aimed at understanding the spectrum of baryon excited states,including both baryons composed of the light u and d quarks,and of the heavier quarks.I then describe recent work aimed at understanding the radiative transitions between baryons,and in particular the N-Roper transition.I conclude with the prospects for future calculations.     

Magnetic Monopoles in U(1)4 Lattice Gauge Theory with Wilson Action

We construct the Euclidean Green functions for the soliton (magnetic monopole) field in the U(1)₄ Lattice Gauge Theory with Wilson action. We show that in the strong coupling regime there is monopole condensation while in the QED phase the physical Hilbert space splits into orthogonal soliton sectors labeled by integer magnetic charge. Received: 2 July 1997 / Accepted: 20 July 1998     

Monodromy fields on ℤ2

Lattice monodromy fields are defined and the massive scaling regime is controlled.     

Anisotropic pairing with repulsive interactions in a model with different orbitals per site

An extension of the Hubbard model, with two orbitals of different symmetry per site is studied. When the two orbitals are hybridized by crystal field effects, the BCS approximation shows that the model has an instability towards anisotropic superconductivity. The competition between superconductivity and antiferromagnetism, and the relevance of other pairing mechanisms, like the Kohn-Luttinger instability, are also analyzed.Received: 1st December 2003, Published online: 30 January 2004PACS: 71.10.Fd Lattice fermion models (Hubbard model, etc.) - 74.20.Mn Nonconventional mechanisms     

Reduction formulae for Euclidean Lattice Theories

LSZ reduction formulae for Euclidean Lattice Theories are presented.Partially supported by CNPq