M. Kirsch

Measurement of the {ital {bar p}}{ital p}{r_arrow}{bar {Lambda}}{Lambda} and {ital {bar p}}{ital p}{r_arrow}{bar {Sigma}}{sup 0}{Lambda}+c.c. reactions at 1.726 and 1.771 GeV/{ital c}

Interest in the production of hyperon-antihyperon pairs following antiproton-proton annihilation stems largely from attempts to understand the nature of flavor production. To date the major focus of both the experimental and the theoretical effort has been on the p¯p??¯? reaction. In this paper, we present data on the complementary channels p¯p?S¯ 0? and p¯p??¯S0. Events from the kinematically similar p¯p??¯? reaction were obtained in parallel. The procedure to distinguish these three separate reactions is described and results for all channels are presented. These include the total and differential cross sections, hyperon polarizations, and spin correlation coefficients. Data were obtained at incident antiproton lab momenta of 1.726 and 1.771 GeV/c which correspond to excess kinetic energies in the p¯p??¯S0+c.c. reaction of 26 and 40 MeV, respectively, above threshold. Comparisons are made to earlier work at similar excess energies in the p¯p??¯? channel. The low-energy regime has been highlighted in this experiment to reduce the complexity in the theoretical analysis.

Investigation of the reaction p̄p→iΛ̄Λ close to threshold at LEAR

The production of antihyperon‐hyperon pairs out of the antiproton‐proton collison has been studied by the PS185 collaboration using the Low Energy Antiproton Ring (LEAR) at CERN. The emphasis of the studies is to investigate the production threshold region. Results obtained for the reactions pp→ΛΛ and pp→ΛΣ°=c.c. are presented and discussed. Total‐ and differential cross sections were measured, polarizations, spin correlations and singlet fractions were extracted at a variety of incident antiproton momenta.The investigations of the collaboration concentrated on the ΛΛ‐final channel. Data on pp→ΛΛ are a vailable for a rather wide energy range. A few results on the ΛΣ channel were analyzed as well as some events for the pp→Σ+Σ+ reaction. Further investigations on the charged sigma final hyperon‐antihyperon pairs are planned and in progress.