Spin structure of $\bar{p}p\rightarrow\bar{\Lambda}\Lambda$

Abstract

A complete determination of spin observables for $\bar{p}p\rightarrow\bar{\Lambda}\Lambda$, at an antiproton lab momentum of 1.637 GeV/c, has been made by the PS185 Collaboration. Results of this experiment disagree strongly with the predictions of calculations which used either meson exchange or quark models for the reaction mechanism. We use a model-independent description of the spin structure of this reaction to show that, in the absence of initial and final state interactions, pure spin singlet or pure spin triplet reaction mechanisms require that depolarization D _nn and spin transfer K _nn are equal, in disagreement with experiment. We also show that a superposition of singlet and triplet reaction mechanisms allow D _nn  ≠ K _nn , as required by experiment.