Measurement of spin-transfer observables in pp → ΛΛ at 1. 637 GeV/c

Spin-transfer observables for pp → ΛΛ have been measured using a transversely polarized frozen-spin target and a beam momentum of 1.637 GeV/c. Current models of the reaction near threshold are in good agreement with existing measurements performed with unpolarized particles in the initial state but produce conflicting predictions for the spin-transfer observables D n n and K n n (the normal-to-normal depolarization and polarization transfer), which are measurable only with polarized target or beam. Measurements of D n n and K n n presented here are found to be in disagreement with predictions from these models.