Política educacional no Brasil: educação técnica e abandono escolar

Lüscher, Ana Zuleima; Dore, Rosemary

doi:10.21713/2358-2332.2011.v8.244

Cited by 18 publications

(18 citation statements)

References 3 publications

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“…In the continuum, they are all equivalent, but on the lattice they can have very different discretization effects. The gluonic definition, utilizing various smearing techniques to damp UV fluctuations, such as the gradient flow (GF) [9][10][11] that we use in this paper, is computationally relatively cheap to calculate and is currently widely used, for example, in the aforementioned nEDM calculation [8]. In this paper we focus on a fermionic definition using the method of spectral projectors [2,12], but we also compare the results to ones from a GF-smeared gluonic definition.…”

Section: Introductionmentioning

confidence: 99%

Topological susceptibility from twisted mass fermions using spectral projectors and the gradient flow

et al. 2018

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We compare lattice QCD determinations of topological susceptibility using a gluonic definition from the gradient flow and a fermionic definition from the spectral projector method.We use ensembles with dynamical light, strange and charm flavors of maximally twisted mass fermions. For both definitions of the susceptibility we employ ensembles at three values of the lattice spacing and several quark masses at each spacing. The data are fitted to chiral perturbation theory predictions with a discretization term to determine the continuum chiral condensate in the massless limit and estimate the overall discretization errors. We find that both approaches lead to compatible results in the continuum limit, but the gluonic ones are much more affected by cut-off effects. This finally yields a much smaller total error in the spectral projector results. We show that there exists, in principle, a value of the spectral cutoff which would completely eliminate discretization effects in the topological susceptibility. *

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Section: Introductionmentioning

confidence: 99%

Topological susceptibility from twisted mass fermions using spectral projectors and the gradient flow

et al. 2018

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“…However, the smearing radius must be small compared to the Compton wavelength of the pion, i.e. R smear 1/M π [16,17]. For physical pion masses this inequality seems reasonably well satisfied for smearing radii up to a few tenths of a fermi.…”

Section: The Correlation Functions In Chptmentioning

confidence: 97%

“…The discreteness of the nucleon and pion momenta due to a finite spatial volume is taken into account. In addition, the mapping of smeared nucleon interpolating fields, commonly used in lattice calculations, to ChPT has been put on firmer grounds [16,17]. More importantly, having results for six instead of only one observable we find the Nπ-state contribution in all six observables to be related.…”

Section: Introductionmentioning

confidence: 94%

Multi-hadron-state contamination in nucleon observables from chiral perturbation theory

Bär

2018

EPJ Web Conf.

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Multi-particle states with additional pions are expected to be a non-negligible source of the excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory (ChPT) can be employed to calculate the contamination due to two-particle nucleon-pion states in various nucleon observables. Results to leading order are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions: the average quark momentum fraction, the helicity and the transversity moment. Taking into account experimental and phenomenological results for the charges and moments the impact of the nucleon-pionstates on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution leads to an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. Existing lattice data is not in conflict with the ChPT predictions, but the comparison suggests that significantly larger source-sink separations are needed to compute the charges and moments with few-percent precision. 1 The precise relation between infinite volume resonance properties and the finite volume energy spectrum has been worked out first in Ref. [3].

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“…No additional fit parameters enter if the N π contribution is included in a simultaneous fit of all ratios and the effective mass. 7 In that sense LO ChPT makes definite predictions: The LO N π contributions are given in terms of the LO single nucleon contributions.…”

Section: N π Contribution In the 3pt Functionsmentioning

confidence: 99%

“…In addition, the mapping of smeared interpolating fields, commonly used in lattice calculations, to ChPT has been put on firmer grounds. 7,8 The goal of this review is to summarize the results of Refs. 3,5,6.…”

Section: Introductionmentioning

confidence: 99%

Chiral perturbation theory and nucleon–pion-state contaminations in lattice QCD

Bär

2017

Int. J. Mod. Phys. A

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Multi-particle states with additional pions are expected to be a non-negligible source of excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory can be employed to calculate the contamination due to two-particle nucleon-pion states in various nucleon observables. Leading order results are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions (quark momentum fraction, helicity and transversity moment). Taking into account phenomenological results for the charges and moments the impact of the nucleon-pion-states on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution results in an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. The source-sink separations accessible in contemporary lattice simulations are found to be too small for chiral perturbation theory to be directly applicable.

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Política educacional no Brasil: educação técnica e abandono escolar

Cited by 18 publications

References 3 publications

Topological susceptibility from twisted mass fermions using spectral projectors and the gradient flow

Topological susceptibility from twisted mass fermions using spectral projectors and the gradient flow

Multi-hadron-state contamination in nucleon observables from chiral perturbation theory

Chiral perturbation theory and nucleon–pion-state contaminations in lattice QCD

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