Practical all-to-all propagators for lattice QCD

Foley, J.; Juge, Keisuke Jimmy; Cais, Alan Ó.; Peardon, Mike; Ryan, Sinéad M.; Skullerud, Jon-Ivar

doi:10.1016/j.cpc.2005.06.008

Cited by 316 publications

(357 citation statements)

References 18 publications

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“…in order to improve the measurements [45]. However, these disconnected contributions are particularly hard to calculate not just because they require the all-to-all propagators but also because they are noise-dominated [46].…”

Section: Simulation Parametersmentioning

confidence: 99%

Quark transverse charge densities in the from lattice QCD

et al. 2009

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We extend the formalism relating electromagnetic form factors to transverse quark charge densities in the light-front frame to the case of a spin-3/2 baryon and calculate these transverse densities for the ∆(1232) isobar using lattice QCD. The transverse charge densities for a transversely polarized spin-3/2 particle are characterized by monopole, dipole, quadrupole, and octupole patterns representing the structure beyond that of a pure point-like spin-3/2 particle. We present lattice QCD results for the ∆-isobar electromagnetic form factors for pion masses down to approximatively 350 MeV for three cases: quenched QCD, two-degenerate flavors of dynamical Wilson quarks, and three flavors of quarks using a mixed action that combines domain wall valence quarks and dynamical staggered sea quarks. We extract transverse quark charge densities from these lattice results and find that the ∆ is prolately deformed, as indicated by the fact that the quadrupole moment G E2 (0) is larger than the value −3 characterizing a point particle and the fact that the transverse charge density in a ∆ + of maximal transverse spin projection is elongated along the axis of the spin.

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Section: Simulation Parametersmentioning

confidence: 99%

Quark transverse charge densities in the from lattice QCD

et al. 2009

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“…An essential step towards a significant reduction of the introduced intrinsic stochastic noise is taken by restricting the support of the source vector to individual timeslices, spacetime points, Dirac or color components. This technique is referred to as dilution [8], and amounts to breaking up a single vector into N d vectors, each consisting of fewer non-zero random numbers Z i . It can be illustrated as follows…”

Section: Stochastic Volume Sourcesmentioning

confidence: 99%

“…Refs. [3,4,5,6,7,8,9,10,11,12,13]), but usually a large computational effort and an appropriately chosen dilution scheme are required in order to sufficiently reduce the intrinsic stochastic noise.…”

Section: Introductionmentioning

confidence: 99%

Variance reduction with practical all-to-all lattice propagators

Endress¹,

Peña²,

Sivalingam³

2015

Computer Physics Communications

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Abstract:We discuss all-to-all quark propagator techniques in two (related) contexts within Lattice QCD: the computation of closed quark propagators, and applications to the so-called "eye diagrams" appearing in the computation of non-leptonic kaon decay amplitudes. Combinations of low-mode averaging and diluted stochastic volume sources that yield optimal signal-to-noise ratios for the latter problem are developed. We also apply a recently proposed probing algorithm to compute directly the diagonal of the inverse Dirac operator, and compare its performance with that of stochastic methods. At fixed computational cost the two procedures yield comparable signal-to-noise ratios, but probing has practical advantages which make it a promising tool for a wide range of applications in Lattice

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“…Hadronic correlation functions which involve quark disconnected contributions are notoriously hard to compute in lattice QCD [1,2]. Such contributions however appear in several quantities related to properties of flavour singlet particles (e.g.…”

Section: Introductionmentioning

confidence: 99%

Quark disconnected diagrams in chiral perturbation theory

Morte

Jüttner

2010

J. High Energ. Phys.

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Abstract:We show how quark-disconnected and quark-connected contributions to hadronic n-point functions can be written as independent correlators for which one can derive expressions in partially quenched chiral effective theory. As an example we apply the idea to the case of the hadronic vacuum polarisation. In particular, we consider the cases of the N f = 2 theory without and with a partially quenched strange quark and also the N f = 2 + 1 theory. In the latter two cases a parameter-free prediction for the disconnected contribution at NLO in the effective theory is given. Finally we show how twisted boundary conditions can then be used in lattice QCD to improve the q 2 resolution in the connected contributions even when flavour singlet operators are considered.

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Practical all-to-all propagators for lattice QCD

Cited by 316 publications

References 18 publications

Quark transverse charge densities in the from lattice QCD

Quark transverse charge densities in the from lattice QCD

Variance reduction with practical all-to-all lattice propagators

Quark disconnected diagrams in chiral perturbation theory

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