Polarized antiquark flavor asymmetry: Pauli blocking vs. the pion cloud

Abstract

The flavor asymmetry of the unpolarized antiquark distributions in the proton, dbar(x) - ubar(x) > 0, can qualitatively be explained either by Pauli blocking by the valence quarks, or as an effect of the pion cloud of the nucleon. In contrast, predictions for the polarized asymmetry Delta_ubar(x) - Delta_dbar(x) based on rho meson contributions disagree even in sign with the Pauli blocking picture. We show that in the meson cloud picture a large positive Delta_ubar(x) - Delta_dbar(x) is obtained from pi-N - sigma-N interference-type contributions, as suggested by chiral symmetry. This effect restores the equivalence of the 'quark' and 'meson' descriptions also in the polarized case.

4 pages, revtex, 3 eps figures

References in corpus (2)

• Polarized light-antiquark distributions in a meson-cloud model
• The flavour asymmetry of polarized anti-quarks in the nucleon

Cited by in corpus (10)

• Extraction of Spin-Dependent Parton Densities and Their Uncertainties
• Quark helicity distributions in the nucleon for up, down, and strange quarks from semi--inclusive deep--inelastic scattering
• The Spin Structure of the Nucleon
• Flavor Structure of the Nucleon Sea
• Chiral dynamics and the growth of the nucleon's gluonic transverse size at small x
• QCD Spin Physics: Partonic Spin Structure of the Nucleon
• Collinear parton distributions and the structure of the nucleon sea in a light-front meson-cloud model
• Sigma Meson Cloud and Proton's Light Flavor Sea Quarks
• The spin dependent structure functions of the nucleon
• Quark-antiquark asymmetry of helicity distributions in the nucleon sea