On strangeness production in the reactions pp -> p Lambda⁰ K+ and pn -> n Lambda⁰ K+ near threshold

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The cross sections for the reactions pp -> p Lambda⁰K+ and pn -> n Lambda⁰K+ are calculated near threshold of the final states. The theoretical ratio of the cross sections R = sigma(pn -> n Lambda⁰K+)/ sigma(pp ->pΛ⁰K+) = 3 shows the enhancement of the pn interaction with respect to the pp interaction near threshold of the strangeness production N Lambda⁰K+. Such an enhancement is caused by the contribution of the np interaction in the isospin-singlet state, which is stronger than the pn interaction in the isospin-triplet state. For the confirmation of this result we calculate the cross sections for the reactions pp -> pp pi⁰, pi⁰ p -> Lambda⁰ K+ and pi-p -> Lambda⁰ K⁰ near threshold of the final states. The theoretical cross sections agree well with the experimental data.