Lambda polarization in polarized proton-proton collisions at BNL RHIC

Abstract

We discuss Λ polarization in inclusive proton-proton collisions, with one of the protons longitudinally polarized. The hyperfine interaction responsible for the Δ-N and Σ-Λ mass splittings gives rise to flavor asymmetric fragmentation functions and to sizable polarized non-strange fragmentation functions. We predict large positive Λ polarization in polarized inclusive proton-proton collisions at large rapidities of the produced Λ. The effect of Σ0 and Σ* decays is also discussed. Forthcoming experiments at RHIC will be able to test our predictions.