Meson-Meson Scattering in Lattice QED_2+1

Scattering phase shifts of a meson-meson system in staggered 3-dimensional lattice QED are computed. The main task of the simulation is to obtain a discrete set of two-body energy levels. These are extracted from a 4-point time correlation matrix and then used to obtain scattering phase shifts. The results for the l=0 and l=2 partial waves are consistent with short- range repulsion and intermediate-range attraction of the residual meson- meson interaction

A study of colour field distributions in the baryon

The distributions of chromo-electric and chromo-magnetic field associated with flux tubes in the baryon are studied in SU(3) lattice QCD. Maximal Abelian projection is used to reduce the statistical fluctuations. For a fixed source geometry, many different string configurations are possible. We investigated whether the string configuration, that is the choice of operator, biases the observed flux distribution.Comment: 3 pages, 3 figures, talk given at Lattice2003(topology

Topology and Staggered Fermion Action Improvement

It is conventional wisdom that staggered fermions do not feel gauge field topology. However, the response of staggered fermion eigenmodes to the topology of the gauge field can depend quite sensitively on the way in which the staggered fermion action is improved. We study this issue using a variety of improved staggered quark actions. We observe that the separation between the ``would be'' zero modes and the non-chiral modes increases with the level of improvement. This enables the ``zero modes'' to be identified unambiguously. The distribution of the remaining non-chiral modes is compared with the predictions of Random Matrix Theory. Satisfactory agreement is obtained.Comment: Lattice 2004 (topology

The rho meson decay constant using a tadpole-improved action

The rho meson decay constant and the associated renormalization factor are computed in the quenched approximation on coarse lattices using a tadpole-improved action which is corrected at the classical level to O(a^2). The improvement is displayed by comparing to Wilson action calculations.Comment: Talk presented at LATTICE96(improvement), 3 pages, LaTeX, uses epsf and espcrc2.st

Heavy-light meson spectrum with and without NRQCD

Results for the spectrum of S and P-wave charmed mesons are obtained in the quenched approximation from a tadpole-improved anisotropic gauge field action and a D234 quark action. This is compared to the spectrum obtained from an NRQCD charm quark and a D234 light antiquark. NRQCD results for bottom mesons are also discussed.Comment: 4 pages, 5 figures. Lattice 2000 (Heavy Quark Physics

Two-body spectra of pseudoscalar mesons with an O(a2)O(a^2)--improved lattice action using Wilson fermions

We extend our calculations with the second-order tree-level and tadpole improved next-nearest-neighbor action to meson-meson systems. Correlation matrices built from interpolating fields representing two pseudoscalar mesons (pion-pion) with relative momenta p are diagonalized, and the mass spectrum is extracted. Link variable fuzzing and operator smearing at both sinks and sources is employed. Calculations are presented for two values of the hopping parameter. The spectrum is used to discuss the residual interaction in the meson-meson system.Comment: 3 pages, 4 EPS figures, Poster presented at "Lattice'97", to appear in the proceeding

Strange matrix elements of the nucleon

Results for the disconnected contributions to matrix elements of the vector current and scalar density have been obtained for the nucleon from the Wilson action at beta=6 using a stochastic estimator technique and 2000 quenched configurations. Various methods for analysis are employed and chiral extrapolations are discussed.Comment: Lattice2002(matrixel), 3 pages, 3 figure

P-wave heavy-light mesons using NRQCD and D234

The masses of S- and P-wave heavy-light mesons are computed in quenched QCD using a classically and tadpole-improved action on anisotropic lattices. Of particular interest are the splittings among P-wave states, which have not yet been resolved experimentally; even the ordering of these states continues to be discussed in the literature. The present work leads to upper bounds for these splittings, and is suggestive, but not conclusive, about the ordering.Comment: LATTICE99(heavy quarks) - 3 pages including 3 figure

S-wave charmed mesons in lattice NRQCD

Heavy-light mesons can be studied using the 1/M expansion of NRQCD, provided the heavy quark mass is sufficiently large. Calculations of the S-wave charmed meson masses from a classically and tadpole-improved action are presented. A comparison of O(1/M), O(1/M^2) and O(1/M^3) results allows convergence of the expansion to be discussed. It is shown that the form of discretized heavy quark propagation must be chosen carefully.Comment: LATTICE98(heavyqk), 3 pages including 3 figure

The charmed and bottom meson spectrum from lattice NRQCD

The mass spectrum of S and P-wave mesons containing a single heavy quark has been computed using quenched lattice nonrelativistic QCD. Numerical results have been obtained at first, second and third order in the heavy quark expansion, so convergence can be discussed. The computed spectrum of charmed and bottom mesons is compared to existing model calculations and experimental data.Comment: 4 pages, 3 figures. To be published in the proceedings of the 4th International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 200