The Quark-Antiquark Asymmetry of the Nucleon Sea from $Λ$ and $\barΛ$ Fragmentation

Abstract

We present a general analysis of the spin transfer for $Λ$ and $\barΛ$ production in deep-inelastic scattering of polarized charged leptons on the nucleon, and find that the pattern of different behaviors of $Λ$ and $\barΛ$ production observed by the E665 Collaboration suggests the possibility of quark-antiquark asymmetries either in the quark to $Λ$ 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 $Λ$ and $\barΛ$ 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 $Λ$ fragmentation functions, provided that the E665 data are confirmed.