Intermediate-energy semileptonic probes of the hadronic neutral current

Musolf, M. J.; Donnelly, T. W.; Dubach, J.; Pollock, Steven J.; Kowalski, S.; Beise, E. J.

doi:10.1016/0370-1573(94)90040-x

Cited by 313 publications

(426 citation statements)

References 196 publications

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“…The 4 He nucleus is spin zero, parity even, and isoscalar. The PV asymmetry takes a much simpler form [4],…”

Section: A and R T =0mentioning

confidence: 99%

“…Nuclear corrections are only relevant for nonhydrogen targets. For the two 4 He measurements, according to Ref. [24], 3% is assigned as the fractional theoretical uncertainty of A nvs .…”

Section: Global Analysis a A Nvs And Theoretical Uncertaintiesmentioning

confidence: 99%

“…elastic e-p scattering, quasielastic e-d scattering, and elastic e- 4 He scattering [4]. In very general terms, the parity-violating asymmetry A PV can be written as…”

mentioning

confidence: 99%

“…Summary of parameters (with some uncertainties in parentheses) in Eqs. (2), (3), and (4). The values of α,ŝ 2 Z , G F , M p , g A /g V are taken directly from Ref.…”

mentioning

confidence: 99%

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Global analysis of nucleon strange form factors at lowQ2

2007

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We perform a global analysis of all recent experimental data from elastic parity-violating electron scattering at low Q 2 . The values of the electric and magnetic strange form factors of the nucleon are determined at Q 2 = 0.1 GeV/c 2 to be G s E = −0.008 ± 0.016 and G s M = 0.29 ± 0.21.DOI: 10.1103/PhysRevC.76.025202 PACS number(s): 11.30. Er, 13.40.Gp, 13.60.Fz The existence of a "sea" of quarks and antiquarks in the nucleon has been firmly established in deep-inelastic lepton scattering experiments as well as in the production of dilepton pairs (the Drell-Yan process). However, demonstrating the role of theseqq pairs in the static electromagnetic properties of the nucleon has been a more elusive and difficult task.As the lightest quark that contributes only to the qq sea, the strange quark provides a unique window on the role of the sea in the nucleon's electromagnetic structure. As suggested by Kaplan and Manohar [1], knowledge of neutral current form factors, when combined with electromagnetic form factors, provides access to the contribution of strange quarks to these form factors. At low momentum transfers, the neutral current form factors can be determined through parity-violating (PV) electron scattering experiments [2,3].During the last decade, there has been dramatic progress in the study of the strange quark-antiquark contributions to the nucleon elastic electromagnetic form factors. A series of definitive PV electron scattering experiments along with several theoretical studies now provides a basis for extracting precision information on these strange quark contributions. In this work we report the results of a global analysis of all these experiments, including both the latest data obtained in experiments performed at the Jefferson Laboratory and the appropriate theoretical input on radiative corrections, and obtain values for the strange electric and magnetic form factors of the nucleon at a four-momentum transfer Q 2 = 0.1 GeV/c 2 . We have also studied the sub-leading Q 2 dependence of these two form factors and found that so far the data do not provide conclusive information. I. STRANGE FORM FACTORS AND PARITY-VIOLATING ELECTRON SCATTERINGThe nucleon vector strange form factors, G s E and G s M , characterize the contribution of the strange sea quarks to the nucleon electromagnetic form factors, and thereby their contribution to the charge and magnetization distributions in the nucleon. where A nvs is the "non-vector-strange" asymmetry (independent of G s E and G s M ) and η E and η M are functions of kinematic quantities, nucleon electromagnetic form factors, and nuclear models (for nonhydrogen targets).For elastic e-p scattering, the full form of the asymmetry is [4]where M p is the mass of the proton and θ is the electron scattering angle. In Eq. (2), G F and α are the Fermi and fine structure constants, respectively. Q 2 is the four-momentum transfer. G (p,n) E,M are the proton and neutron electric and magnetic form factors, while G e A is the proton axial form factor seen by an elec...

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“…The 4 He nucleus is spin zero, parity even, and isoscalar. The PV asymmetry takes a much simpler form [4],…”

Section: A and R T =0mentioning

confidence: 99%

“…Nuclear corrections are only relevant for nonhydrogen targets. For the two 4 He measurements, according to Ref. [24], 3% is assigned as the fractional theoretical uncertainty of A nvs .…”

Section: Global Analysis a A Nvs And Theoretical Uncertaintiesmentioning

confidence: 99%

“…elastic e-p scattering, quasielastic e-d scattering, and elastic e- 4 He scattering [4]. In very general terms, the parity-violating asymmetry A PV can be written as…”

mentioning

confidence: 99%

“…Summary of parameters (with some uncertainties in parentheses) in Eqs. (2), (3), and (4). The values of α,ŝ 2 Z , G F , M p , g A /g V are taken directly from Ref.…”

mentioning

confidence: 99%

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Global analysis of nucleon strange form factors at lowQ2

2007

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“…Early polarized deep-inelastic scattering (DIS) experiments suggested that a surprisingly large fraction of the proton's spin might be carried by strange quarks [1], in contrast to the naive quark model expectations [2]. Recognition that the spatial distributions of strange quarks and antiquarks could be different further motivated searches for strange contributions to the nucleon's electroweak form factors [3][4][5][6][7][8]. Dedicated programs of strange form factor measurements through parityviolating electron scattering at Jefferson Lab and other facilities [9][10][11] subsequently yielded very precise determinations of both the strange electric and magnetic form factors of the nucleon [12], enabling rigorous comparisons with lattice QCD and chiral effective theory [13,14], as well as fundamental tests of the Standard Model [15].…”

Section: Introductionmentioning

confidence: 99%

Strange-quark asymmetry in the proton in chiral effective theory

Wang

Melnitchouk

et al. 2016

Phys. Rev. D

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We perform a comprehensive analysis of the strange-antistrange parton distribution function (PDF) asymmetry in the proton in the framework of chiral effective theory, including the full set of lowest order kaon loop diagrams with off-shell and contact interactions, in addition to the usual on-shell contributions previously discussed in the literature. We identify the presence of δ-function contributions to thes PDF at x = 0, with a corresponding valence-like component of the s-quark PDF at larger x, which allows greater flexibility for the shape of s −s. Expanding the moments of the PDFs in terms of the pseudoscalar kaon mass, we compute the leading nonanalytic behavior of the number and momentum integrals of the s ands distributions, consistent with the chiral symmetry of QCD. We discuss the implications of our results for the understanding of the NuTeV anomaly and for the phenomenology of strange quark PDFs in global QCD analysis.

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Nucleon Knockout by Intermediate Energy Electrons

Kelly

Advances in Nuclear Physics

133

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Intermediate-energy semileptonic probes of the hadronic neutral current

Cited by 313 publications

References 196 publications

Global analysis of nucleon strange form factors at lowQ2

Global analysis of nucleon strange form factors at lowQ2

Strange-quark asymmetry in the proton in chiral effective theory

Nucleon Knockout by Intermediate Energy Electrons

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