Searcharxiv⌕ Search

arXiv subjects

S. Furui

Publications and source records attributed to S. Furui.

5 recordsLinked to original sources
arXiv1999

Test of the Kugo-Ojima Confinement Criterion in the Lattice Landau Gauge

We present the first results of numerical test of the Kugo-Ojima confinement criterion in the lattice Landau gauge. The Kugo-Ojima criterion of colour confinement in the BRS formulation of the continuum gauge theory is given by $u_b^a(p^2)=-δ_b^a$, where $u_b^a$ is defined by the two point function of the Faddeev-Popov ghost fields $c, \bar c$ and the gauge field $A_μ$. We measured the lattice version of $u_b^a(0)$ in use of $1/(-\partial D(A))$ where $D_μ(A)$ is a lattice covariant derivative in the new definition of the gauge fields as $U=e^A$. We obtained that $u_b^a(0)$ is consistent with $-cδ_b^a, c=0.7$ in SU(3) quenched simulation data of $β=5.5$ on $8^4$ and $12^4$. We report the $β$ dependence and finite-size effect of c.

hep-lat↗
arXiv1998

Gluon Propagator in the Landau Gauge fixed Lattice QCD Simulation

We measured the gluon propagator in the Landau gauge fixed QCD Langevin simulation and studied the infra-red behaviour of the gluon propagator. The 4^3 x 8 lattice simulation was done for quenched $β=3,4,5$ and unquenched $β=4, κ=0.1,0.15,0.2$ using each 100 independent samples. The Landau gauge fixing was done by an extension of the Fourier acceleration method with the condition Max|div A|<10^{-4}, and the field A is related to the link variable by U=exp A instead of the usual U-linear definition. We confirmed gauge fixing with smearing preconditioning works perfectly for the purpose of finding the global minimum of the squared norm of the gauge field when $β$ is large(e.g. $β=5$). Our simulation results suggests the possibility of a realization of the infrared behaviour of the Gribov-Zwanziger theory.

hep-lat↗
arXiv1996

A new algorithm for numerical simulation of Langevin equations

Formulated is a new systematic method for obtaining higher order corrections in numerical simulation of stochastic differential equations (SDEs), i.e., Langevin equations. Random walk step algorithms within a given order of finite $Δt$, are obtained so as to reproduce within that order a corresponding transition density of the Fokker-Planck equations, in the weak Taylor approximation scheme. A great advantage of our method is its straightforwardness such that direct perturbative calculations produce the algorithm as an end result, so that the procedure is tractable by computer. Examples in general form for curved space cases as well as flat space cases are given in some order of approximations. Simulations are performed for specific examples of U(1) system and SU(2) systems, respectively.

hep-lat↗
arXiv1994

An Analysis of Four-quark Energies in SU(2) Lattice Monte Carlo using the Flux-tube Symmetry:

Energies of four-quark systems calculated by the static quenched SU(2) lattice Monte Carlo method are analyzed in $2\times 2$ bases for square, rectangle, tilted rectangle, linear and quadrilateral geometry configurations and in $3\times 3$ bases for a non-planar geometry configuration. For small interquark distances, a lattice effect is taken into account by considering perimeter dependent terms which are characterized by the cubic symmetry. It is then found that a parameter $f$ - that can be identified as a gluon field overlap factor - is rather well described by the form $exp(-[b_sE{\cal A}+\sqrt{b_s}F{\cal P}])$, where ${\cal A}$ and ${\cal P}$ are the area and perimeter mainly defined by the positions of the four quarks, $b_s$ is the string constant in the 2-quark potentials and $E,F$ are constants.

hep-lat↗