Stranger Still: Kaon Loops and Strange Quark Matrix Elements of the Nucleon

Abstract

Intrinsic strangeness contributions to low-energy strange quark matrix elements of the nucleon are modelled using kaon loops and meson-nucleon vertex functions taken from nucleon-nucleon and nucleon-hyperon scattering. A comparison with pion loop contributions to the nucleon electromagnetic (EM) form factors indicates the presence of significant SU(3)-breaking in the mean-square charge radii. As a numerical consequence, the kaon loop contribution to the mean square Dirac strangeness radius is significantly smaller than could be observed with parity-violating elastic ep experiments planned for CEBAF, while the contribution to the Sachs radius is large enough to be observed with PV electron scattering from (0^+,0) nuclei. Kaon loops generate a strange magnetic moment of the same scale as the isoscalar EM magnetic moment and a strange axial vector form factor having roughly one-third magnitude extracted from nu p/nubar p elastic scattering. In the chiral limit, the loop contribution to the fraction of the nucleon's scalar density arising from strange quarks has roughly the same magnitude as the value extracted from analyses of Sigma_{πN}. The importance of satisfying the Ward-Takahashi Identity, not obeyed by previous calculations, is also illustrated, and the sensitivity of results to input parameters is analyzed.

18 Tex pages and 2 figures (postscript files included), CEBAF Theory pre-print #TH-93-01

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• The Strangeness Radius and Magnetic Moment of the Nucleon Revisited
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• QCD Equalities for Baryon Current Matrix Elements
• Strangeness in the Nucleon on the Light-Cone
• Strangeness spin, magnetic moment and strangeness configurations of the proton
• Locality of the Strange Sea in the Nucleon
• Stranger in the Light: The Strange Vector Form Factors of the Nucleon
• Chiral Symmetry and the Nucleon's Vector Strangeness Form Factors
• Strange Asymmetries in the Nucleon Sea
• Spectral Content of Isoscalar Nucleon Form Factors
• Static properties of chiral models with SU(3) group structure
• Strangeness Form Factors of the Proton in the Chiral Quark Model
• Strange Form Factors of Baryons
• Many-Body Currents and the Strange-Quark Content of 4he
• Parton distributions from nonlocal chiral SU(3) effective theory. I. Splitting functions
• The Strangeness Magnetic Moment of the Proton in the Chiral Quark Model
• Flavor structure of the octet magnetic moments
• Dispersion Analysis of the Strange Vector Form Factors of the Nucleon
• Nucleon Strangeness and Unitarity
• K^* Mesons and Nucleon Strangeness
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• Strangeness in the proton and N*(1535)
• Electromagnetic Gauge Invariance of the Cloudy Bag Model
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• Strange vector form factors of the nucleon in the SU(3) chiral quark-soliton model with the proper kaonic cloud
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• Nucleon Vector Strangeness Form Factors: Multi-pion Continuum and the OZI Rule
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• Essential Strangeness in Nucleon Magnetic Moments
• Nucleon Strange Magnetic Moment and Relativistic Covariance
• Deuteron Electroweak Disintegration
• Heavy-quark contribution to the proton's magnetic moment
• Octet and decuplet baryon self-energies in relativistic SU(3) chiral effective theory
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• Parity violating target asymmetry in electron - proton scattering