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The differential and total cross sections for kaon pair production in the pp → ppK + K − reaction have been measured at three beam energies of 2.65, 2.70, and 2.83 GeV using the ANKE magnetic spectrometer at the COSY-Jülich accelerator. These near-threshold data are separated into pairs arising from the decay of the φ-meson and the remainder. For the non-φ selection, the ratio of the differential cross sections in terms of the K − p and K + p invariant masses is strongly peaked towards low masses. This effect can be described quantitatively by using a simple ansatz for the K − p final state interaction, where it is seen that the data are sensitive to the magnitude of an effective K − p scattering length. When allowance is made for a small number of φ events where the K − rescatters from the proton, the φ region is equally well described at all three energies. A very similar phenomenon is discovered in the ratio of the cross sections as functions of the K − pp and K + pp invariant masses and the identical final state interaction model is also very successful here. The world data on the energy dependence of the non-φ total cross section is also reproduced, except possibly for the results closest to threshold.

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Exclusive measurements of the quasi-free np → npπ 0 π 0 reaction have been performed by means of dp collisions at T d = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region √ s = (2.35-2.46) GeV, which includes the region of the ABC effect and its associated d * (2380) resonance. Adding the d * resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of Fäldt and Wilkin as well with those of Albadajedo and Oset. The ABC effect, i.e. the low-mass enhancement in the π 0 π 0 -invariant mass spectrum, is found to be very modest -if present at all, which might pose a problem to some of its interpretations.