Comparison of Λ and Σ⁰ production near threshold in proton-proton collisions

Threshold measurements of the associated strangeness production reactions pp → pK+ Λ and pp → pK+ Σ 0 are presented. The most remarkable feature of the data is that at the same excess energy the total cross section for the Σ0 production appears to be about a factor of 28+6− 9 smaller than for the Σ particle. It is concluded that strong Σ0p final state interactions, and in particular the Σ → Λp conversion reaction, are the likely cause of the depletion in the Σ signal. This hypothesis is in line with other experimental evidence in the literature. © 1999 The American Physical Society.