The Quark-Antiquark Asymmetry of the Nucleon Sea from $\Lambda$ and $\bar{\Lambda }$ Fragmentation

Abstract

We present a general analysis of the spin transfer for $\Lambda$ and $\bar{\Lambda }$ production in deep-inelastic scattering of polarized charged leptons on the nucleon, and find that the pattern of different behaviors of $\Lambda$ and $\bar{\Lambda }$ production observed by the E665 Collaboration suggests the possibility of quark-antiquark asymmetries either in the quark to $\Lambda$ fragmentation functions and/or in the quark and antiquark distributions of the target proton. We also point out that the strange-antistrange asymmetry of the nucleon sea may produce an observable contribution to the different behaviors of $\Lambda$ and $\bar{\Lambda }$ production. We find that a softer $\bar{s}(x)$ than $s(x)$ as predicted by the light-cone baryon-meson fluctuation model of intrinsic quark-antiquark pairs of the nucleon sea might lead to a reasonable picture. However, the magnitude is still too small to explain the E665 data and the conclusion has also strong model-dependence. This may suggest the importance of quark-antiquark asymmetry in the quark to $\Lambda$ fragmentation functions, provided that the E665 data are confirmed.

15 latex pages, 2 figures

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• Longitudinal Polarization of Lambda and anti-Lambda Hyperons in Lepton-Nucleon Deep-Inelastic Scattering
• Nucleon strange $s\bar{s}$ asymmetry to the $\Lambda /\bar{\Lambda }$ fragmentation
• Quark Fragmentation Functions in a Diquark Model for $\Lambda$ Production
• Strange quark-antiquark asymmetry of nucleon sea from $\Lambda /\bar{\Lambda }$ polarization
• On Reconciling Gottfried Sum Rule Violation with Cabibbo Theory