Multigrid solver for clover fermions

Osborn, James C.; Clark, Matt; Babich, Ronald; Brannick, James; Cohen, Saul D.; Brower, R. C.; Rebbi, C.

doi:10.48550/arxiv.1011.2775

Cited by 14 publications

(22 citation statements)

References 4 publications

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“…Second, we are leveraging a powerful new adaptive multigrid (MG) algorithm for inverting the Wilson-clover Dirac operator that is allowing us to compute the disconnected diagrams for both strange and light quarks at very little additional cost [64,65]. We are also taking advantage of clusters accelerated by graphics processing units (GPUs) using the QUDA library [66,67], which provides another substantial speedup.…”

Section: Discussionmentioning

confidence: 99%

Exploring strange nucleon form factors on the lattice

et al. 2012

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We discuss techniques for evaluating sea quark contributions to hadronic form factors on the lattice and apply these to an exploratory calculation of the strange electromagnetic, axial, and scalar form factors of the nucleon. We employ the Wilson gauge and fermion actions on an anisotropic 24 3 × 64 lattice, probing a range of momentum transfer with Q 2 < 1 GeV 2 . The strange electric and magnetic form factors, G s E (Q 2 ) and G s M (Q 2 ), are found to be small and consistent with zero within the statistics of our calculation. The lattice data favor a small negative value for the strange axial form factor G s A (Q 2 ) and exhibit a strong signal for the bare strange scalar matrix element N |ss|N 0. We discuss the unique systematic uncertainties affecting the latter quantity relative to the continuum, as well as prospects for improving future determinations with Wilson-like fermions.

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Section: Discussionmentioning

confidence: 99%

Exploring strange nucleon form factors on the lattice

et al. 2012

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“…It is, therefore, efficient to precondition the matrix by deflating the low-eigenmodes. We implement such improvement using the multigrid solver [22,23] which has deflation built in. To obtain the LP estimate of the two-point function, we truncate the multigrid solver using a low-accuracy stopping criterion: the ratio (r LP ≡ |residue| LP /|source|) is chosen to be 10 −3 for all the ensembles.…”

Section: A Two-point Functionmentioning

confidence: 99%

Isovector and isoscalar tensor charges of the nucleon from lattice QCD

et al. 2015

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We present results for the isovector and flavor diagonal tensor charges g needed to probe novel tensor interactions at the TeV scale in neutron and nuclear β-decays and the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The lattice QCD calculations were done using nine ensembles of gauge configurations generated by the MILC collaboration using the HISQ action with 2+1+1 dynamical flavors. These ensembles span three lattice spacings a ≈ 0.06, 0.09 and 0.12 fm and three quark masses corresponding to the pion masses Mπ ≈ 130, 220 and 310 MeV. Using estimates from these ensembles, we quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, volume and light quark masses for the connected contributions. The final estimates of the connected nucleon (proton) tensor charge for the isovector combination is g u−d T = 1.020(76) in the MS scheme at 2 GeV. The additional disconnected quark loop contributions needed for the flavor-diagonal matrix elements are calculated using a stochastic estimator employing the truncated solver method with the all-mode-averaging technique. We find that the size of the disconnected contribution is smaller than the statistical error in the connected contribution. This allows us to bound the disconnected contribution and include it as an additional uncertainty in the flavor-diagonal charges. After a continuum extrapolation, we find g

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“…These savings have been demonstrated in the original DD-HMC setup [14] as well as in mass preconditioned HMC [12]. A very similar idea is the adaptive multi-grid [15].…”

Section: Solvermentioning

confidence: 99%

Algorithms for lattice QCD: progress and challenges

Schaefer¹

2011

AIP Conference Proceedings

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Abstract. The development of improved algorithms for QCD on the lattice has enabled us to do calculations at small quark masses and get control over the chiral extrapolation. Also finer lattices have become possible, however, a severe slowing down associated with the topology of the gauge fields has been observed. This may prevent simulations of lattices fine enough for controlling the continuum extrapolation. This conference contribution introduces the basic concepts behind contemporary lattice algorithms, the current knowledge about their slowing down towards the continuum and its consequences for future lattice simulations.

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Multigrid solver for clover fermions

Cited by 14 publications

References 4 publications

Exploring strange nucleon form factors on the lattice

Exploring strange nucleon form factors on the lattice

Isovector and isoscalar tensor charges of the nucleon from lattice QCD

Algorithms for lattice QCD: progress and challenges

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