Comparison of Lambda and Sigma(0) production near threshold in proton-proton collisions

Threshold measurements of the associated strangeness production reactions p p --> pK(+)Lambda and pp --> pK(+)Sigma(0) are presented. The most remarkab le feature of the data is that at the same excess energy the total cross se ction 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 con version reaction, are the likely cause of the depletion in the Sigma signal . This hypothesis is in line with other experimental evidence in the litera ture.