The quark-antiquark asymmetry of the nucleon sea from Lambda and (Lambda)over-bar fragmentation

We present a general analysis of the spin transfer for Lambda and production in deep-inelastic scattering of polarized charged leptons on the nucleon, and find that the pattern of different behaviors of Lambda and 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 production. We find that a softer (s) over bar(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. (C) 2000 Elsevier Science B.V. All rights reserved.