Bounds on transverse spin asymmetries for Λ baryon production in pp collisions at BNL RHIC

We study inclusive Λ hyperon production in pp collisions at BNL RHIC, with just one transversely polarized proton. We show that the measurement of the spin transfer between the initial proton and the produced Λ is sensitive to the proton transversity distributions and to the corresponding Λ transversity fragmentation functions. In view of our present ignorance of these distributions and fragmentation functions, we resort to positivity bounds for making some predictions for the corresponding spin transfer asymmetry.