Energy dependence of the Lambda/Sigma0 production cross section ratio in p-p interactions


The production of the Lambda and Sigma0 hyperons has been measured via the pp->pK+Lambda / Sigma0 reaction at the internal COSY-11 facility in the excess energy range between 14 and 60 MeV. The transition of the Lambda / Sigma0 cross section ratio from about 28 at Q <= 13 MeV to the high energy level of about 2.5 is covered by the data showing a strong decrease of the ratio between 10 and 20 MeV excess energy.
The strength of the final state interactions in the p-Sigma0 channel seems to be much smaller compared to the p-Lambda one. Estimates of the effective range parameters are given for the N Lambda and the N Sigma0 systems.

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Eur.Phys.Jou. A 22 (2004) 293-299