Quark structure of Λ from Λ polarization in Z decays -: art. no. 034017

The flavor and spin structure for the quark distributions of the Lambda baryon is studied in a perturbative QCD (PQCD) analysis and in the SU(6) quark-diquark model, and then applied to calculate the A polarization of semi-inclusive Lambda production in e(+)e(-) annihilation near the Z pole. It is found that the quark-diquark model gives a very good description of the available experimental data. The PQCD model can also give a good description of the data by taking inter account the suppression of quark helicities compared to the naive SU(6) quark model spin distributions. Further information is required for a clean distinction between different predictions concerning the flavor and spin structure of the Lambda.