Strange nucleon form factors: Solitonic approach to GM s , GE s , $ \tilde{{G}}_{{A}}^{{p}}$ and $ \tilde{{G}}_{{A}}^{{n}}$ and comparison with world data

Goeke, K.; Kim, Hyun-Chul; Silva, António; Urbano, Diana

doi:10.1140/epja/i2006-10398-7

Cited by 16 publications

(17 citation statements)

References 34 publications

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“…[36][37][38]. As a result, the strange vector form factors were predicted and turned out to be within the uncertainty of the experimental data [39]. The first calculation of the tensor charges of the nucleon in the QSM has already been carried out many years ago [40,41].…”

Section: Introductionmentioning

confidence: 98%

Transverse strange quark spin structure of the nucleon

Ledwig

Kim

2012

Phys. Rev. D

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We investigate the transverse quark spin densities of the nucleon with the lowest moment within the framework of the SU(3) chiral quark-soliton model, emphasizing the strange quark spin density. Based on previous results of the vector and tensor form factors, we are able to determine the impact-parameter dependent probability densities of transversely polarized quarks in an unpolarized nucleon as well as those of unpolarized quarks in a transversely polarized nucleon. We find that the present numerical results for the transverse spin densities of the up and down quarks are in good agreement with those of the lattice calculation. We predict the transvere spin densities of the strange quark. It turns out that the polarized strange quark is noticeably distorted in an unpolarized proton.Comment: 10 pages. 16 figures. Submitted to Physical Review

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Section: Introductionmentioning

confidence: 98%

Transverse strange quark spin structure of the nucleon

Ledwig

Kim

2012

Phys. Rev. D

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“…The strange quark contribution to the electromagnetic form factors of the nucleon can be expressed in terms of the strange electric and magnetic form factors G s E and G s M . There are various theoretical approaches for estimating the strange form factors [1,2], such as quark soliton models [3,4,5], chiral quark models [6], quenched lattice calculations [7] or two-component models [8]. Parity violating electron scattering provides a direct experimental approach [9,10,11].…”

mentioning

confidence: 99%

Measurement of Strange Quark Contributions to the Vector Form Factors of the Proton atQ2=0.22 (GeV/c)2

Baunack¹,

Aulenbacher²,

Ríos³

et al. 2009

Phys. Rev. Lett.

119

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A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q 2 ¼ 0:22 ðGeV=cÞ 2 is reported here. The measured asymmetry is A LR ¼ ðÀ17:23 AE 0:82 stat AE 0:89 syst Þ Â 10 À6 . The standard model prediction assuming no strangeness is A 0 ¼ ðÀ15:87 AE 1:22Þ Â 10 À6 . In combination with previous results from measurements at forward angles, it is possible to disentangle for the first time the strange form factors at this momentum transfer, G s E ¼ 0:050 AE 0:038 AE 0:019 and G s M ¼ À0:14 AE 0:11 AE 0:11. DOI: 10.1103/PhysRevLett.102.151803 PACS numbers: 13.40.Gp, 11.30.Er, 12.15.Ày, 14.20.Dh Sea quarks are an important ingredient to describe nucleon properties in terms of fundamental QCD degrees of freedom. Strange quark-antiquark pairs might play a relevant role and affect, e.g., the electromagnetic properties of the nucleon. The contribution of strange quarks to the charge radius and magnetic moment in the nucleon ground state is of specific interest since this is a pure sea quark effect. The strange quark contribution to the electromagnetic form factors of the nucleon can be expressed in terms of the strange electric and magnetic form factors G s E and G s M . There are various theoretical approaches for estimating the strange form factors [1,2], such as quark soliton models [3][4][5], chiral quark models [6], quenched lattice calculations [7], or two-component models [8]. Parity violating electron scattering provides a direct experimental approach [9][10][11].A measurement of parity violation necessarily involves a weak interaction probe of the nucleon. This provides additional information allowing a measurement of G s E and G s M . Within the standard model of electroweak interaction, it is known that electromagnetic and weak currents are related. Assuming isospin symmetry, the weak vector form factors G p E;M of the proton, describing the vector coupling to the Z 0 boson, can be expressed in terms of the electromagnetic nucleon form factors G p;n E;M and the strange form factors G s E;M . The interference between tree level electromagnetic and weak amplitudes leads to a parity violating asymmetry in the elastic scattering cross section of left-and righthanded electrons (LR) L , R :This asymmetry can be written as a sum of three terms, A LR ¼ A V þ A S þ A A . A V represents the vector coupling on the proton vertex without strangeness contribution, A S contains the strange quark vector contribution, and A A represents the axial coupling to the proton vertex [11]: PRL 102, 151803 (2009)

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“…In addition to the extensive experimental activity, a variety of theoretical models have been applied to the calculation of the strange nucleon form factors. These approaches include the QCD equalities supplemented with constituent quark model assumptions [17], heavy baryon chiral perturbation theory [18,19], dispersive approaches [20,21,22], vector dominance model (VDM) [23], VDM with a kaon cloud contribution [24], the Skyrme model [25], the NJL model [26], the chiral soliton [27,28], chiral bag [29] and chiral quark models [30,31,32], a two-component model with a meson cloud [33], etc. These theoretical predictions vary quite widely.…”

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confidence: 99%

Strange magnetic form factor of the proton atQ2=0.23 GeV2

et al. 2009

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We determine the u and d quark contributions to the proton magnetic form factor at finite momentum transfer by applying chiral corrections to quenched lattice data. Heavy baryon chiral perturbation theory is applied at next to leading order in the quenched, and full QCD cases for the valence sector using finite range regularization. Under the assumption of charge symmetry these values can be combined with the experimental values of the proton and neutron magnetic form factors to deduce a relatively accurate value for the strange magnetic form factor at Q 2 = 0.23 GeV 2 , namely G s M = −0.034 ± 0.021 µ N .

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Strange nucleon form factors: Solitonic approach to GM s , GE s , $ \tilde{{G}}_{{A}}^{{p}}$ and $ \tilde{{G}}_{{A}}^{{n}}$ and comparison with world data

Cited by 16 publications

References 34 publications

Transverse strange quark spin structure of the nucleon

Transverse strange quark spin structure of the nucleon

Measurement of Strange Quark Contributions to the Vector Form Factors of the Proton atQ2=0.22 (GeV/c)2

Strange magnetic form factor of the proton atQ2=0.23 GeV2

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