Nucleon axial form factor from lattice QCD

Liu, K. F.; Dong, Shao-Jing; Draper, Terrence; Jimin, Wu; Wilcox, Walter

doi:10.1103/physrevd.49.4755

Cited by 50 publications

(84 citation statements)

References 30 publications

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“…Fortunately, it is relatively straightforward to compute g A in numerical lattice QCD simulations. In spite of this, there is still no consensus as regards g A from lattice QCD [2,3,4,5,6,7,8,9]. In fact, a trend toward under predicting [2,3,4] g A has led to some controversy regarding the possibility of large finite-volume effects [10,11].…”

Section: Introductionmentioning

confidence: 99%

Baryon axial charge in a finite volume

2004

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Section: Introductionmentioning

confidence: 99%

Baryon axial charge in a finite volume

2004

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“…Recently, lattice QCD simulations for the nucleon became available for Q 2 = 0 [69][70][71][72][73][74][75][76], for finite Q 2 [77][78][79][80][81][82][83], and also for the octet baryons [84][85][86][87]. These studies are very important to understand the role of the valence quarks and of the meson cloud dressing.…”

Section: Introductionmentioning

confidence: 99%

Axial form factors of the octet baryons in a covariant quark model

Ramalho

Tsushima

2016

Phys. Rev. D

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We study the weak interaction axial form factors of the octet baryons, within the covariant spectator quark model, focusing on the dependence of four-momentum transfer squared, Q 2 . In our model the axial form factors GA(Q 2 ) (axial-vector form factor) and GP (Q 2 ) (induced pseudoscalar form factor), are calculated based on the constituent quark axial form factors and the octet baryon wave functions. The quark axial current is parametrized by the two constituent quark form factors, the axial-vector form factor g q A (Q 2 ), and the induced pseudoscalar form factor g q P (Q 2 ). The baryon wave functions are composed of a dominant S-state and a P -state mixture for the relative angular momentum of the quarks. First, we study in detail the nucleon case. We assume that the quark axial-vector form factor g q A (Q 2 ) has the same function form as that of the quark electromagnetic isovector form factor. The remaining parameters of the model, the P -state mixture and the Q 2 -dependence of g q P (Q 2 ), are determined by a fit to the nucleon axial form factor data obtained by lattice QCD simulations with large pion masses. In this lattice QCD regime the meson cloud effects are small, and the physics associated with the valence quarks can be better calibrated. Once the valence quark model is calibrated, we extend the model to the physical regime, and use the low Q 2 experimental data to estimate the meson cloud contributions for GA(Q 2 ) and GP (Q 2 ). Using the calibrated quark axial form factors, and the generalization of the nucleon wave function for the other octet baryon members, we make predictions for all the possible weak interaction axial form factors GA(Q 2 ) and GP (Q 2 ) of the octet baryons. The results are compared with the corresponding experimental data for GA(0), and with the estimates of baryon-meson models based on SU (6) symmetry.

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“…Lattice calculations of three-point functions have been used to study the EM [13], axial (isovector) [14], pseudoscalar(πNN) [15] form factors, and the flavor-singlet g 0 A [12]. For the scalar current, we use S(x) = 2κ/8κ c [ūu(x) +dd(x)], where we have implemented the mean-field improvement factor 8κ c to define the lattice operator [16].…”

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πNσterm,s¯sin the nucleon, and the scalar form factor: A lattice study

1996

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We report on a lattice QCD calculation of the πN σ term, the scalar form factor, and N |ss|N . The disconnected insertion part of σ πN is found to be 1.8 ± 0.1 times larger than the connected insertion contribution. The q 2 dependence of σ πN (q 2 ) is about the same as G E (q 2 ) of the proton so that σ πN (2m 2 π )−σ πN (0) = 6.6±0.6 MeV. The ratio y = N |ss|N / N |ūu+dd|N = 0.36 ± 0.03. Both results favor a σ πN ∼ 53 MeV, slightly larger than our direct calculation of σ πN = 49.7 ± 2.6 MeV. We also compute F s and D s and find that the agreement with those from the octect baryon mass splittings crucially depends on the inclusion of the large disconnected insertion. Finally, we give our result for the KN σ term.

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Nucleon axial form factor from lattice QCD

Cited by 50 publications

References 30 publications

Baryon axial charge in a finite volume

Baryon axial charge in a finite volume

Axial form factors of the octet baryons in a covariant quark model

πNσterm,s¯sin the nucleon, and the scalar form factor: A lattice study

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