Differential and total cross sections for the pp → ppK + K − reaction have been measured at a proton beam energy of 2.83 GeV using the COSY-ANKE magnetic spectrometer. Detailed model descriptions fitted to a variety of one-dimensional distributions permit the separation of the pp → ppφ cross section from that of non-φ production. The differential spectra show that higher partial waves represent the majority of the pp → ppφ total cross section at an excess energy of 76 MeV, whose energy dependence would then seem to require some s-wave φp enhancement near threshold. The non-φ data can be described in terms of the combined effects of two-body final state interactions using the same effective scattering parameters determined from lower energy data.

The transverse spin correlations Ax,x and Ay,y have been measured in the d p → pspec{pp}sπ − reaction at COSY-ANKE at 353 MeV per nucleon. Here {pp}s denotes a proton-proton pair with low excitation energy, which is dominantly in the 1 S0 state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton pspec so that the reaction could be interpreted in terms of quasi-free n p → {pp}sπ − . The proton analyzing power in this reaction was also deduced from this data set by averaging over the polarization of the deuteron beam. The values of A p y were shown to be consistent with a refined analysis of our earlier results obtained with a polarized proton incident on a deuterium target. Taking these data in combination with our previous measurements of the differential cross sections and analyzing powers in the pp → {pp}s π 0 reaction, a more robust partial wave decomposition was achieved. Three different acceptable solutions were found and the only way of resolving this ambiguity without further theoretical input would be through a measurement of the mixed spin-correlation parameter Ax,z.