Low-lying eigenmodes of the Wilson-Dirac operator and correlations with topological objects

The probability density of low-lying eigenvectors of the hermitian Wilson-Dirac operator is examined. Comparisons in position and size between eigenvectors, topological charge and action density are made. We do this for standard Monte-Carlo generated SU(3) background fields and for single instanton background fields. Both hot and cooled SU(3) background fields are considered. An instanton model is fitted to eigenmodes and topological charge density and the sizes and positions of these are compared.Comment: v3: 20 pages, 11 figures, Colour versions of Fig. 1 and Fig. 4 and additional colour figures can be obtained at http://www.physics.adelaide.edu.au/cssm/lattice Revised version contains additional discussions about the topological charge used and greatly improved readability of the plots, Corrected Fig.

Meson properties from lattice QCD

Quantum Chromo - Dynamics ( QCD ) is the part of the Standard Model which describes the interaction of the strong nuclear force with matter. QCD is asymptotically free, so at high energies perturbation expansions in the coupling can be used to calculate expectation values. Away from this limit, however, perturbation expansions in the coupling do not converge. Lattice QCD ( LQCD ) is a non - perturbative approach to calculations in QCD. LQCD first performs a Wick rotation t → - it [subscript E], and then discretises spacetime into a regular lattice with some lattice spacing a. QCD is then expressed in terms of parallel transport operators of the gauge field between grid points, and fermion fields which are defined at the grid points. Operators are evaluated in terms of these quantities, and the lattice spacing is then taken to zero to recover continuum values. We perform computer simulations of Lattice QCD in order to extract a variety of meson observables. In particular, we perform a comprehensive survey of the light and strange meson octets, obtain for the first time exotic meson results consistent with experiment, calculate the charge form - factor of the light and strange pseudoscalar mesons, and determine ( for the first time in Lattice QCD ) all three form - factors of the vector meson.Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Physics, Centre for the Subatomic Structure of Matter, 2007

Hybrid mesons on the lattice with FLIC fermions

The spectral properties of hybrid meson interpolating fields are investigated. The quantum numbers of the meson are carried by smeared-source fermion operators and highly-improved chromo-electric and -magnetic field operators composed with APE-smeared links. The effective masses of standard and hybrid operators indicate that the ground state meson is effectively isolated using both standard and hybrid interpolating fields. Focus is placed on interpolating fields in which the large spinor components of the quark and antiquark fields are merged. In particular, the effective mass of the exotic 1"-"+ meson is reported. Further, we report some values for excited mesonic states using a variational process. (orig.)Available from TIB Hannover: RA 2999(03-208) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Hybrid meson spectrum from the FLIC action

The spectral properties of hybrid meson interpolating fields are investigated. The quantum numbers of the meson are carried by smeared-source fermion operators and highly-improved chromo-electric and -magnetic field operators composed with APE-smeared links. The effective masses of standard and hybrid operators indicate that the ground state meson is effectively isolated using both standard and hybrid interpolating fields. Focus is placed on interpolating fields in which the large spinor components of the quark and antiquark fields are merged. In particular, the effective mass of the exotic 1"-"+ meson is reported. Further, we report some values for excited mesonic states using a variational process. (orig.)Available from TIB Hannover: RA 2999(03-207) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman