Lambda_b-Polarization from its Inclusive Semileptonic Decay

Abstract

We discuss the Lambda_b-polarization of the bottom baryon Lambda_b in its production and in its decay. Standard Model predictions for b-quark polarization on the Z-peak are reviewed, including beam-quark orientation effects and O(as) radiative corrections to the polarization. The b-quark polarization is expected to be handed over to the Lambda_b into which it fragments with a high degree of efficiency. We present several spin-momentum correlation measures of the spin of the Λ_b with the momenta of its decay products in its inclusive semileptonic decay. We estimate the strengths of the spin-momentum correlations in the Free Quark Decay (FQD) model and find that some of the measures provide good or very good analyzing power for measuring the polarization of the Lambda_b.