Eur. Phys. J. A (2004) 22: 293-299
https://doi.org/10.1140/epja/i2003-10236-6

Energy dependence of the Λ/Σproduction cross-section ratio in p-p interactions

¹ Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany
² Institut für Kernphysik, Westfälische Wilhelms-Universität, D-48149, Münster, Germany
³ Institute of Nuclear Physics, PL-31 342, Cracow, Poland
⁴ Institute of Physics, Jagellonian University, PL-30 059, Cracow, Poland
⁵ Institute of Physics, University of Silesia, PL-40 007, Katowice, Poland
⁶ Zentrallabor für Elektronik, Forschungszentrum Jülich, D-52425, Jülich, Germany

^* e-mail: p.kowina@fz-juelich.de

Received: 21 July 2003
Accepted: 28 May 2004
Published online: 3 November 2004

Abstract

The production of the Λ- and Σ⁰-hyperons has been measured via the pp → pK ⁺Λ/Σ⁰ reaction at the internal COSY-11 facility in the excess energy range between 14 and 60 MeV. The transition of the Λ/Σ⁰ 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. Effects from the final-state interactions in the p-Σ⁰ channel seem to be much smaller than in the p-Λ channel. Estimates of the effective range parameters are given for the NΛ and the NΣ systems.