Comparison ofΛandΣ0Production near Threshold in Proton-Proton Collisions

Threshold measurements of the associated strangeness production reactions pp --> pK(+)Lambda and pp --> pK(+)Sigma(0) are presented. The most remarkable feature of the data is that at the same excess energy the total cross section for the Sigma(0) production appears to be about a factor of 28(-9)(+6) smaller than for the Lambda particle. It is concluded that strong Sigma(0)p final state interactions, and in particular the Sigma N --> Lambda p conversion reaction, are the likely cause of the depletion in the Sigma signal. This hypothesis is in line with other experimental evidence in the literature.