Stochastic estimation with Z2 noise

Dong, Shao-Jing; Liu, Keh-Fei

doi:10.1016/0370-2693(94)90440-5

Cited by 175 publications

(153 citation statements)

References 13 publications

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“…More recently, applications to three-point functions have shown their effectiveness for form factor calculations [7,9]. We consider the use of Z(2) ⊗ Z (2) random noisy source as introduced in [17].…”

Section: B Choice Of Momenta Carried By Quarksmentioning

confidence: 99%

“…2 we present our method to calculate the pion form factor. In order to access the region of small momentum transfer, we use the method of partially twisted boundary condition [11][12][13][14], and in order to fight increasing computational cost for smaller pion mass, we apply the method of random wall source [9,[15][16][17][18][19]. In addition we make use of a judicious choice of momenta carried by the incoming and outgoing quarks off the electromagnetic vertex, which helps in reducing statistical fluctuations in the form factor measurements.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electromagnetic form factor of pion from N f = 2 + 1 dynamical flavor QCD

Nguyen

Ishikawa

Ukawa

et al. 2011

J. High Energ. Phys.

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We present a calculation of the electromagnetic form factor of the pion in N f = 2+1 flavor lattice QCD. Calculations are made on the PACS-CS gauge field configurations generated using Iwasaki gauge action and Wilson-clover quark action on a 32 3 × 64 lattice volume with the lattice spacing estimated as a = 0.0907(13) fm at the physical point. Measurements of the form factor are made using the technique of partially twisted boundary condition to reach small momentum transfer as well as periodic boundary condition with integer momenta.Additional improvements including random wall source techniques and a judicious choice of momenta carried by the incoming and outgoing quarks are employed for error reduction.Analyzing the form factor data for the pion mass at M π ≈ 411 MeV and 296 MeV, we find that the NNLO SU(2) chiral perturbation theory fit yields r 2 = 0.441 ± 0.046 fm 2 for the pion charge radius at the physical pion mass. Albeit the error is quite large, this is consistent with the experimental value of 0.452 ± 0.011 fm 2 . Below M π ≈ 300 MeV, we find that statistical fluctuations in the pion two-and three-point functions become too large to extract statistically meaningful averages on a 32 3 spatial volume. We carry out a sample calculation on a 64 4 lattice with the quark masses close to the physical point, which suggests that form factor calculations at the physical point become feasible by enlarging lattice sizes to M π L ≈ 4.

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Section: B Choice Of Momenta Carried By Quarksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electromagnetic form factor of pion from N f = 2 + 1 dynamical flavor QCD

Nguyen

Ishikawa

Ukawa

et al. 2011

J. High Energ. Phys.

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“…The number of low-modes is set to N e = 160. The contribution of the remaining high-modes is estimated by the noise method [8]. For each configuration, we prepare a complex Z 2 noise vector η(x), which is diluted into…”

Section: Pos(lattice 2015)121mentioning

confidence: 99%

Nucleon axial and tensor charges with dynamical overlap quarks

Yamanaka¹,

Ohki²,

Hashimoto³

et al. 2016

Proceedings of the 33rd International Symposium on Lattice Field Theory — PoS(LATTICE 2015)

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We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses m π = 450 and 540 MeV.

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“…To reduce its variance, stochastic volume sources (SVS) [11] and dilution [12] techniques are used to estimate S h stochastically. That is, low-mode averaging is combined with stochastic sources (LMA + SVS).…”

Section: Pos(lattice 2012)131mentioning

confidence: 99%

Variance reduction techniques for a quantitative understanding of the Delta I=1/2 rule

Endress¹,

Peña²

2012

Proceedings of the 30th International Symposium on Lattice Field Theory — PoS(Lattice 2012)

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The role of the charm quark in the dynamics underlying the ∆I = 1/2 rule for kaon decays can be understood by studying the dependence of kaon decay amplitudes on the charm quark mass using an effective ∆S = 1 weak Hamiltonian in which the charm is kept as an active degree of freedom. Overlap fermions are employed in order to avoid renormalization problems, as well as to allow access to the deep chiral regime. Quenched results in the GIM limit have shown that a significant part of the enhancement is purely due to low-energy QCD effects; variance reduction techniques based on low-mode averaging were instrumental in determining the relevant weak effective lowenergy couplings in this case. Moving away from the GIM limit requires the computation of diagrams containing closed quark loops. We report on our progress to employ a combination of low-mode averaging and stochastic volume sources in order to control these contributions.Results showing a significant improvement in the statistical signal are presented.

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Stochastic estimation with Z2 noise

Cited by 175 publications

References 13 publications

Electromagnetic form factor of pion from N f = 2 + 1 dynamical flavor QCD

Electromagnetic form factor of pion from N f = 2 + 1 dynamical flavor QCD

Nucleon axial and tensor charges with dynamical overlap quarks

Variance reduction techniques for a quantitative understanding of the Delta I=1/2 rule

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