Measurement of the Cross Section Ratio for Lambda and Sigma0 Production


In recent threshold studies of hyperon production at COSY-11 the cross section ratio of sigma(pp->pK+Lambda) / sigma(pp->pK+Sigma0) was found to be in the order of 30 in contradiction to a ratio of about 2.5 measured at higher excess energies (epsilon > 350 MeV). Different scenarios were proposed to explain this unexpected behaviour, but the present data are not suffcient to discriminate between possible explanations. Therefore it is proposed to study the transition of the cross section ratio of Lambda / Sigma0 production in the pp interaction from threshold values to the high energy level.

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