184 citations · 485 across the 24 of their papers we have counts for
25 papers · 1 filter
Towards the glueball spectrum from unquenched lattice QCD
E. Gregory, A. Irving, B. Lucini +4
We use a variational technique to study heavy glueballs on gauge configurations generated with 2+1 flavours of ASQTAD improved staggered fermions. The variational technique include…
A study of the eta and eta' mesons with improved staggered fermions
Eric B. Gregory, Alan C. Irving, Christopher M. Richards +1
We report on a high statistics lattice QCD calculation of the mass of the eta and eta' mesons using ASQTAD improved staggered fermions. The calculation used two ensembles with diff…
Glueball mass measurements from improved staggered fermion simulations
Christopher M. Richards, Alan C. Irving, Eric B. Gregory +1
We present the first 2+1 flavour spectrum measurements of glueball states using high statistics simulations with improved staggered fermions. We find a spectrum consistent with que…
Pseudoscalar Flavor-Singlet Physics with Staggered Fermions
Eric B. Gregory, Alan Irving, Chris M. Richards +2
Accurately calculating the mass of flavor-singlet meson states from numerical lattice simulations is an important milestone for lattice QCD. Careful measurement of the full pseudos…
Methods for Pseudoscalar Flavour-Singlet Mesons with Staggered Fermions
Eric B. Gregory, Alan C. Irving, Chris M. Richards +1
We present the first 2+1 flavour lattice QCD calculations of pseudoscalar flavour-singlet propagators using improved staggered fermions. We explore the relevant techniques and disc…
Pseudoscalar flavor-singlets and staggered fermions
Eric B. Gregory, Alan C. Irving, Craig McNeile +1
The Asqtad improved staggered fermion formalism has been a valuable tool in successfully calculating the non-singlet parts of the hadronic spectrum. We are engaged in a project to…
Determining the strange quark mass for 2-flavour QCD
M. Göckeler, R. Horsley, A. C. Irving +5
Using the O(a) Symanzik improved action an estimate is given for the strange quark mass for unquenched (n_f=2) QCD. The determination is via the axial Ward identity (AWI) and inclu…
Matrix elements and baryon spectroscopy from unquenched lattice QCD with improved staggered quarks
Eric B. Gregory, Alan C. Irving, Craig McNeile +2
We look for the effect of open decay channels on the masses of baryons in unquenched lattice QCD. We apply variational smearing using fuzzed basis states to a staggered nucleon ope…
Towards measuring the eta' mass with N_f=2+1 staggered fermions
Eric B. Gregory, Alan Irving, Craig McNeile +2
Because the propagators of flavor-singlet states incorporate disconnected diagrams, they are uniquely sensitive to any differences in the actions governing sea and valence fermions…
Scalar glueball and meson spectroscopy in unquenched lattice QCD with improved staggered quarks
Eric B. Gregory, Alan C. Irving, Craig C. McNeile +2
We present results of an exploratory study of singlet scalar states in unquenched QCD using both glueball and meson operators. Results for non-singlet non-strange scalar mesons are…
The axial charge of the nucleon on the lattice and in chiral perturbation theory
A. Ali Khan, M. Göckeler, P. Hägler +10
We present recent Monte Carlo data for the axial charge of the nucleon obtained by the QCDSF-UKQCD collaboration for N_f=2 dynamical quarks. We compare them with formulae from chir…
Pseudoscalar singlet physics with staggered fermions
Eric B. Gregory, Alan C. Irving, Craig McNeile +2
We report on progress in measuring disconnected correlators associated with pseudoscalar flavor-singlet mesons. This will eventually allow us to compute the masses of the eta and e…
Determination of Lambda in quenched and full QCD - an update
M. Göckeler, R. Horsley, A. C. Irving +4
We present an update on our previous determination of the Lambda parameter in QCD. The main emphasis is on results for two flavours of light dynamical quarks, where we can now almo…
Axial and tensor charge of the nucleon with dynamical fermions
A. Ali Khan, M. Göckeler, P. Hägler +9
We present preliminary results for the axial and tensor charge of the nucleon obtained from simulations with N_f=2 clover fermions. A comparison with chiral perturbation theory is…
Calculation of Finite Size Effects on the Nucleon Mass in Unquenched QCD using Chiral Perturbation Theory
A. Ali Khan, T. Bakeyev, M. Göckeler +7
The finite size effects on nucleon masses are calculated in relativistic chiral perturbation theory. Results are compared with two-flavor lattice results.
Chiral Perturbation Theory and Finite Size Effects on the Nucleon Mass in unquenched QCD
A. Ali Khan, T. Bakeyev, M. Göckeler +7
We calculate finite size effects on nucleon masses in chiral perturbation theory. We confront the theoretical predictions with N_f=2 lattice results and discuss chiral extrapolatio…
Effects of non-perturbatively improved dynamical fermions in UKQCD simulations
Alan C. Irving, UKQCD Collaboration
We present results for QCD with 2 degenerate flavours of quark using a non-perturbatively improved action on a lattice volume of where the bare gauge coupling and ba…
Instability in the Molecular Dynamics Step of Hybrid Monte Carlo in Dynamical Fermion Lattice QCD Simulations
Balint Joo, Brian Pendleton, Anthony D. Kennedy +5
We investigate instability and reversibility within Hybrid Monte Carlo simulations using a non-perturbatively improved Wilson action. We demonstrate the onset of instability as tol…
Numerical Stability of Lanczos Methods
Eamonn Cahill, Alan Irving, Christopher Johnson +1
The Lanczos algorithm for matrix tridiagonalisation suffers from strong numerical instability in finite precision arithmetic when applied to evaluate matrix eigenvalues. The mechan…
Parallel Tempering in Lattice QCD with O(a)-Improved Wilson Fermions
Balint Joo, Alan C Irving, James C. Sexton +4
We present details of our investigation of the Parallel Tempering algorithm. We consider the application of action matching technology to the selection of parameters. We then prese…
Tuning Actions and Observables in Lattice QCD
Alan C. Irving, James C. Sexton, Eamonn Cahill +5
We propose a strategy for conducting lattice QCD simulations at fixed volume but variable quark mass so as to investigate the physical effects of dynamical fermions. We present det…
Determination of constant lattice spacing trajectories in lattice QCD
Alan C. Irving, UKQCD Collaboration
We argue that lattice simulations of full QCD with varying quark mass are best conducted at fixed lattice spacing rather than at fixed . We present techniques which enable this…
Approximate actions for dynamical fermions
Alan C. Irving, James C. Sexton, Eamonn Cahill
Recent developments and applications of approximate actions for full lattice QCD are described. We present first results based on the stochastic estimation of the fermion determina…
Approximate Actions for Lattice QCD Simulation
Alan C. Irving, James C. Sexton
We describe a systematic approach to generating approximate actions for the lattice simulation of QCD. Three different tuning conditions are defined to match approximate with true…