Non-perturbative improvement of the anisotropic Wilson QCD action (original) (raw)

Heavy quarks on anisotropic lattices with standard and RG improved actions

Nuclear Physics B - Proceedings Supplements, 2002

On quenched lattice simulations, we examine the relation between the hopping and fermionic anisotropy parameter on anisotropic tattices with the clover O(a) improved action. For the gauge sector we used configurations for the standard and the RG(Iwasaki) improved actions.

The anisotropic Wilson gauge action

Nuclear Physics B, 1998

Anisotropic lattices, with a temporal lattice spacing smaller than the spatial one, allow precision Monte Carlo calculations of problems that are difficult to study otherwise: heavy quarks, glueballs, hybrids, and high temperature thermodynamics, for example. We here perform the first step required for such studies with the (quenched) Wilson gauge action, namely, the determination of the renormalized anisotropy ξ as a function of the bare anisotropy ξ 0 and the coupling. By, essentially, comparing the finite-volume heavy quark potential where the quarks are separated along a spatial direction with that where they are separated along the time direction, we determine the relation between ξ and ξ 0 to a fraction of 1% for weak and to 1% for strong coupling. We present a simple parameterization of this relation for 1 ≤ ξ ≤ 6 and 5.5 ≤ β ≤ ∞, which incorporates the known one-loop result and reproduces our non-perturbative determinations within errors. Besides solving the problem of how to choose the bare anisotropies if one wants to take the continuum limit at fixed renormalized anisotropy, this parameterization also yields accurate estimates of the derivative ∂ξ 0 /∂ξ needed in thermodynamic studies.

Light hadron spectroscopy on the lattice with the non-perturbatively improved Wilson action

1998

We present results for the light meson masses and decay constants as obtained from calculations with the non-perturbatively improved ('Alpha') action and operators on a 24 3 ×64 lattice at β = 6.2, in the quenched approximation. The analysis was performed in a way consistent with O(a) improvement. We obtained: reasonable agreement with experiment for the hyperfine splitting; f K = 156 ± 17 MeV, f π = 139 ± 22 MeV, f K /f π = 1.13(4);

Effective field theory for the anisotropic Wilson lattice action

Physical Review D, 2008

We construct the effective field theory appropriate for describing the low energy behavior of anisotropic Wilson lattice actions and the O(a) improved variant thereof. We then apply this effective field theory to the hadron spectrum and dispersion relations, focussing on the corrections due to the anisotropy. We point out an important feature of anisotropic lattices regarding the Aoki-regime; for a given set of fermion masses and spatial lattice spacing, if an isotropic action is in the QCD-phase, this does not guarantee that the anisotropic action is outside the Aoki-regime. This may be important in the tuning of bare parameters for anisotropic lattices using domain-wall and overlap fermions as well as Wilson and O(a)-improved Wilson fermions.

Symanzik Improvement In The Static Quark Potential

1999

A systematic investigation of Symanzic improvement in the gauge field action is performed for the static quark potential in quenched QCD. We consider Symanzik improved gauge field configurations on a 16^3 X 32 lattice with a relatively coarse lattice spacing of 0.165(2)fm. A matched set of standard Wilson gauge configurations is prepared at \beta = 5.74 with the same physical volume and lattice spacing and is studied for comparison. We find that, despite the coarse lattice spacing, the unimproved and less-expensive Wilson action does as well as the Symanzik action in allowing us to extract the static quark potential at large qqbar separations. We have considered novel methods for stepping off-axis in the static quark potential which provides new insights into the extent to which the ground state potential dominates the Wilson loop correlation function.

Free energies of heavy quarks in full-QCD lattice simulations with Wilson-type quark action

Nuclear Physics A, 2009

The free energy between a static quark and an antiquark is studied by using the color-singlet Polyakov-line correlation at finite temperature in lattice QCD with 2+1 flavors of improved Wilson quarks. From the simulations on 32 3 × 12, 10, 8, 6, 4 lattices in the high temperature phase, based on the fixed scale approach, we find that, the heavy-quark free energies at short distance converge to the heavy-quark potential evaluated from the Wilson loop at zero temperature, in accordance with the expected insensitivity of short distance physics to the temperature. At long distance, the heavy-quark free energies approach to twice the single-quark free energies, implying that the interaction between heavy quarks is screened. The Debye screening mass obtained from the long range behavior of the free energy is compared with the results of thermal perturbation theory.

Improved bilinears in lattice QCD with nondegenerate quarks

Physical Review D, 2006

Simulations of lattice QCD with light dynamical quarks are greatly facilitated by the use of improved actions and operators. Calculations are underway using various types of improved fermions—staggered, domain wall/overlap, maximally twisted and improved Wilson fermions. Here we focus on improved Wilson fermions, and investigate how the improvement program can be extended to remove errors proportional to amq (a is the lattice spacing, and mq a generic quark mass) in the realistic case of nondegenerate quark ...

Finite-size effects in lattice QCD with dynamical Wilson fermions

Physical Review D, 2005

Due to limited computing resources choosing the parameters for a full lattice QCD simulation always amounts to a compromise between the competing objectives of a lattice spacing as small, quarks as light, and a volume as large as possible. Aiming at pushing unquenched simulations with the standard Wilson action towards the computationally expensive regime of small quark masses, the GRAL project addresses the question whether computing time can be saved by sticking to lattices with rather modest numbers of grid sites and extrapolating the finite-volume results to the infinite volume (prior to the usual chiral and continuum extrapolations). In this context we investigate in this work finite-size effects in simulated light hadron masses. Understanding their systematic volume dependence may not only help saving computer time in light quark simulations with the Wilson action, but also guide future simulations with dynamical chiral fermions which for a foreseeable time will be restricted to rather small lattices. We analyze data from hybrid Monte Carlo simulations with the N f = 2 Wilson action at two values of the coupling parameter, β = 5.6 (lattice spacing a ≈ 0.08 fm) and β = 5.32144 (a ≈ 0.13 fm). The larger β corresponds to the coupling used previously by SESAM/TχL. The considered hopping parameters κ = 0.1575, 0.158 (at the larger β) and κ = 0.1665 (at the smaller β) correspond to quark masses of 85, 50 and 36% of the strange quark mass, respectively. At each quark mass we study at least three different lattice extents in the range from L = 10 to L = 24 (0.85-2.04 fm). Estimates of autocorrelation times in the stochastic updating process and of the computational cost of every run are given. For each simulated sea quark mass we calculate quark propagators and hadronic correlation functions in order to extract the pion, rho and nucleon masses as well as the pion decay constant and the quark mass from the PCAC relation. We examine to what extent the volume dependence of the masses can be parameterized by simple functions based on M. Lüscher's analytic formula and previous numerical findings by other groups. The applicability of results for the pion and the nucleon from chiral effective theory in the parameter regime covered by our simulations is discussed. Cutoff effects in the PCAC quark mass are found to be under control. Contents 4.4.

Tuning improved anisotropic actions in lattice perturbation theory

Arxiv preprint arXiv:0810.4477, 2008

In recent years, anisotropic lattice actions have seen increasing use in simulations. The 3+1 anisotropic lattice, which has a temporal lattice spacing at that is much less than the spatial lattice spacing as, is obviously very useful in studies of QCD at non-zero temperature, where it ...