Strangeness production processes p¯p→Y¯Y (Y=Λ,Σ) have been studied near threshold in a full coupled-channel calculation. The transition interactions are based on K- and ${\mathit{K}}^{\mathrm{*}}$-meson exchange. The elastic part of the p¯p and Y¯Y 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 introducing phenomenological optical potentials. First results are presented for the reactions p¯p→Λ¯${\mathrm{\Sigma }}^0$+Σ¯ ${}_{}{}^0{}_{}{}^{}\mathrm{\Lambda }$ as well as p¯p→Σ¯ ${}_{}{}^{\pm }{}_{}{}^{}\mathrm{\Sigma }_{}^{\pm }{}_{}{}^{}$, Σ¯ ${}_{}{}^0{}_{}{}^{}\mathrm{\Sigma }_{}^0{}_{}{}^{}$, which agree with existing data. As in p¯p→Λ¯Λ, tensor and spin-triplet dominance is realized in p¯p→Σ¯ Σ but is somewhat reduced in p¯p→Λ¯ ${\mathrm{\Sigma }}^0$+Σ¯ ${}_{}{}^0{}_{}{}^{}\mathrm{\Lambda }$. Although Σ¯ ${}_{}{}^{\mathrm{-}}{}_{}{}^{}\mathrm{\Sigma }_{}^{\mathrm{-}}{}_{}{}^{}$ cannot be reached from p¯p by a single transition, the corresponding cross section is only slightly smaller than for Σ¯ ${}_{}{}^{+}{}_{}{}^{}\mathrm{\Sigma }_{}^{+}{}_{}{}^{}$. Initial-and final-state effects play a decisive role, even in cross section ratios.

• Received 5 June 1992

DOI:https://doi.org/10.1103/PhysRevC.46.2516