Quenched Light Hadron Spectrum and Decay Constants using Improved Wilson Fermion Actions

We compare results obtained using the Sheikholeslami-Wohlert (SW) fermion action with tree-level and tadpole-improved coefficients for $5.7\le\beta\le 6.2$.Comment: Talk presented at LATTICE96(spectrum), 3 LaTeX pages plus 5 ps figures, espcrc2.sty (included

Is the Quenched Spectrum in agreement with Experiment?

We analyse the meson spectrum in quenched QCD using lattice gauge theory. By studying hadron propagation with a variety of operators (both smeared and local), we are able to extract the ground state and first excited state masses with confidence. We pay attention to the correlations among the data used in the fits to extract these masses and couplings. We compare the resulting hadron spectrum with experiment and find evidence for a significant departure in the pseudoscalar and vector meson masses.Comment: 19 pages, Latex, 8 postscript figures (uuencoded), also available from ftp://suna.amtp.liv.ac.uk/pub/cmi/sl/sl.p

Heavy Hybrids from NRQCD

We present results for the exotic $0^{+-}$ and $1^{-+}$ $b\bar{b}g$ hybrids at $\beta=6.0$. A leading order NRQCD action is used to generate the heavy quark propagators. The optimisation of operators is discussed and we compare our results to the predictions of recent potential calculations.Comment: 3 pages, four figures, Latex, uses espcrc2.sty. Talk presented at LATTICE97, Edinburg

Effects of Dynamical Quarks in UKQCD Simulations

Recent results from the UKQCD Collaboration's dynamical simulations are presented. The main feature of these ensembles is that they have a fixed lattice spacing and volume, but varying sea quark mass from infinite (corresponding to the quenched simulation) down to roughly that of the strange quark mass. The main aim of this work is to uncover dynamical quark effects from these ``matched'' ensembles. We obtain some evidence of dynamical quark effects in the static quark potential with less effects in the hadronic spectrum.Comment: Invited paper presented at the Workshop on Lattice Hadron Physics, July 2001, Cairns, Australia. 7 pages. Uses espcrc2.sty (included

Light hadron spectroscopy with O(a) improved dynamical fermions

We present results for the hadron spectrum and static quark potential from a simulation with two flavours of $O(a)$ improved dynamical Wilson fermions at $\beta=5.2$. We address the issues of sea quark dependence of observables and finite-size effects.Comment: LATTICE98(spectrum), 3 pages, 4 figure

Heavy Meson Spectroscopy at Beta=6.0

We present results of a quenched calculation of the heavy-light and quarkonium spectrum using the tadpole improved clover action. We resolve completely the triplet chi P-states in quarkonium systems, and obtain evidence for fine structure of the heavy-light P-states. Approximate scaling of the hyperfine splittings is observed, producing results that are significantly below experiment.Comment: Contribution to Lattice 97 proceedings: 3 pages, 7 postscript figures, LaTeX2e, uses espcrc2.st

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 (ie including glueball effects). I also review the status of hybrid mesons and their decays.Comment: to appear in proceedings of QNP2002, 3 pages, LATEX, 2 ps figure

Chiral symmetry restoration of QCD and the Gross-Neveu model

Two flavour massless QCD has a second order chiral transition which has been argued to belong to the universality class of the $3d$ O(4) spin model. The arguments have been questioned recently, and the transition was claimed to be mean field behaved. We discuss this issue at the example of the $3d$ Gross-Neveu model. A solution is obtained by applying various well established analytical methods.Comment: LATTICE98(hightemp

Glueballs and Hybrids (Gluons as Constituents)

After a brief introduction to hybrid and glueball source operators, I summarize recent lattice results for these particles.Comment: 5 pages, contribution to LATTICE-99, corrected glueball mass tabl