Meson-exchange and quark-gluon transitions in thep¯p→Λ¯Λ process

Different p¯p→Λ¯Λ transition mechanisms [K+${\mathit{K}}^{\mathrm{*}}$ exchange, K exchange only, and quark-gluon exchange ${(}^3$ ${\mathit{S}}_1$ version)] are investigated in a full coupled-channel (p¯p,Λ¯Λ) calculation. The elastic part of the p¯p and Λ¯Λ interactions has been derived from a one-boson-exchange version of the Bonn NN potential and a corresponding extension to the hyperon-nucleon case whereas the annihilation part is taken into account by phenomenological optical potentials. As expected, results for spin observables differ substantially for the different transition models. It turns out that resulting polarizations and spin correlation parameters are quite sensitive to variations in the initial- and final-state interactions whereas spin-transfer parameters are much more stable in this regard. Therefore, the latter observables, especially the depolarization ${\mathit{D}}_{\mathit{n}\mathit{n}}$, can be used to discriminate between various transition scenarios.