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Polarized antiquark flavor asymmetry \(\mathrm{\Delta \bar u (x) - \Delta \bar d(x)}\) and the pion cloud

Short Note

Abstract.

The flavor asymmetry of the unpolarized antiquark distributions in the proton, \(\bar u(x) - \bar d(x) < 0\), can qualitatively be explained as an effect of the pion cloud. Corresponding predictions have been made for the polarized asymmetry, \(\Delta \bar u(x) - \Delta \bar d(x)\), based on rho-meson contributions. These estimates differ in sign and magnitude from those obtained in quark-based models, which give \(\Delta \bar u(x) - \Delta \bar d(x) > 0\). Using a simple chiral linear sigma model as an example, we demonstrate that in the meson cloud picture a large positive \(\Delta \bar u(x) - \Delta \bar d(x)\) can be obtained from \(\pi\)-\(\sigma\) interference contributions. This calls into question previous estimates based on rho-meson contributions alone, and indicates how the results of the meson cloud picture may be reconciled with those of quark-based models.

Keywords

Sigma Model Previous Estimate Linear Sigma Model Interference Contribution Pion Cloud 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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© Springer-Verlag Berlin/Heidelberg 2003

Authors and Affiliations

  1. 1.Institut für Theoretische PhysikUniversität RegensburgRegensburgGermany
  2. 2.Physics DepartmentDuke UniversityDurhamUSA

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