Polarized Λ-Baryon Production in pp Collisions

We study the production of longitudinally polarized Λ baryons in single-spin pp--> collisions at BNL RHIC and DESY HERA- N--> as a means of determining the spin-dependent Λ fragmentation functions. It is shown that a measurement of the rapidity distribution of the Λ's would provide an excellent way of clearly discriminating between various recently suggested sets of polarized Λ fragmentation functions that are all compatible with present e⁺e^- data. We also address the main theoretical uncertainties, which appear to be well under control.