Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation

Shanahan, Phiala E.; Horsley, R.; Nakamura, Y.; Pleiter, D.; Rakow, P. E. L.; Schierholz, G.; Stüben, H.; Thomas, A. W.; Young, R.; Zanotti, J. M.

doi:10.1103/physrevd.89.074511

Cited by 63 publications

(46 citation statements)

References 64 publications

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“…2 , which is consistent with earlier studies using chiral perturbation theory [79][80][81][82][83][84][85] and chiral extrapolation of lattice QCD data [86][87][88][89]. For example, in our calculation the pion cloud increases the magnitude of the proton and neutron anomalous magnetic moments by 25% and 45%, respectively, giving final results of κ p = 1.78 and κ n = −1.81, which are in rather good agreement with the empirical values.…”

Section: Gevsupporting

confidence: 81%

Role of diquark correlations and the pion cloud in nucleon elastic form factors

2014

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Electromagnetic form factors of the nucleon in the space-like region are investigated within the framework of a covariant and confining Nambu-Jona-Lasinio model. The bound state amplitude of the nucleon is obtained as the solution of a relativistic Faddeev equation, where diquark correlations appear naturally as a consequence of the strong coupling in the colour3 qq channel. Pion degrees of freedom are included as a perturbation to the "quark-core" contribution obtained using the Poincaré covariant Faddeev amplitude. While no model parameters are fit to form factor data, excellent agreement is obtained with the empirical nucleon form factors (including the magnetic moments and radii) where pion loop corrections play a critical role for Q 2 1 GeV 2 . Using charge symmetry, the nucleon form factors can be expressed as proton quark sector form factors. The latter are studied in detail, leading, for example, to the conclusion that the d-quark sector of the Dirac form factor is much softer than the u-quark sector, a consequence of the dominance of scalar diquark correlations in the proton wave function. On the other hand, for the proton quark sector Pauli form factors we find that the effect of the pion cloud and axialvector diquark correlations overcomes the effect of scalar diquark dominance, leading to a larger d-quark anomalous magnetic moment and a form factor in the u-quark sector that is slightly softer than in the d-quark sector.

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Section: Gevsupporting

confidence: 81%

Role of diquark correlations and the pion cloud in nucleon elastic form factors

2014

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“…There has recently been good progress in the calculation of the electromagnetic form factors for the octet baryons [22,23], using chiral extrapolations of the lattice results. Clearly an extension of that work to weak form factors would provide a valuable test our model predictions.…”

Section: Axial Chargesmentioning

confidence: 99%

“…These studies have been complemented by a judicious use of chiral effective field theory in order to extrapolate to the physical quark masses. Thus, we now have quite accurate determinations of the hyperon electric [22] and magnetic [23] form factors up to 1.4 GeV 2 , as well as low moments of their parton distribution functions [24]. It has even been possible recently to shed some light on the proton spin puzzle [25,26] by calculating the spin fractions carried by quarks across the octet [27].…”

Section: Introductionmentioning

confidence: 99%

SU(3)-flavor breaking in octet baryon masses and axial couplings

2014

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The lightest baryon octet is studied within a covariant and confining Nambu-Jona-Lasinio model. By solving the Poincaré covariant Faddeev equations -including scalar and axialvector diquarkswe determine the baryon octet masses and axial charges for strangeness conserving transitions. For the axial charges the degree of violation of SU (3) flavour symmetry, arising because of the strange spectator quark(s), is found to be no more than 10%.

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“…QCD [128][129][130][131][132] have been restricted to relatively low momentum transfers Q 2 3 GeV 2 , because the rapid falloff with Q 2 of the form factors leads to very small signalto-noise ratios in the extraction of hadronic three-point correlators, and related systematic uncertainties due to excited-state contamination, among other issues. Lin et al [133] employed a novel technique using anisotropic lattices with both quenched and dynamical ensembles with m π ≥ 450 MeV to reach Q 2 ≈ 6 GeV 2 .…”

Section: Lattice Qcdmentioning

confidence: 99%