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We report on measurements of the differential cross section $d\ensuremath{\sigma}/d\mathrm{\ensuremath{\Omega}}$ and the first measurement of the analyzing power ${A}_{y}$ in the $\mathrm{\ensuremath{\Delta}}(1232)$ excitation energy region of the reaction $pp\ensuremath{\rightarrow}{{pp}}_{s}{\ensuremath{\pi}}^{0}$ where ${{pp}}_{s}$ is a $^{1}S_{0}$ proton pair. The experiment has been performed with the ANKE spectrometer at COSY-J\"ulich. The data reveal a peak in the energy dependence of the forward ${{pp}}_{s}$ differential cross section, a minimum at zero degrees of its angular distribution, and a large analyzing power. The results present a direct manifestation of two two-baryon resonance-like states with ${J}^{P}={2}^{\ensuremath{-}}$ and ${0}^{\ensuremath{-}}$ and an invariant mass of $2.2\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}/{c}^{2}$.

The transverse spin correlations ${A}_{x,x}$ and ${A}_{y,y}$ have been measured in the $\stackrel{P\vec}{d}\stackrel{P\vec}{p}\ensuremath{\rightarrow}{p}_{\text{spec}}{{pp}}_{s}{\ensuremath{\pi}}^{\ensuremath{-}}$ 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 ${}^{1}{S}_{0}$ state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton ${p}_{\text{spec}}$ so that the reaction could be interpreted in terms of quasifree $\stackrel{P\vec}{n}\phantom{\rule{0.16em}{0ex}}\stackrel{P\vec}{p}\ensuremath{\rightarrow}{{pp}}_{s}{\ensuremath{\pi}}^{\ensuremath{-}}$. The proton and neutron analyzing powers in this reaction were also deduced from this data set by averaging over the polarizations of the deuteron beam and hydrogen target, respectively. The values of ${A}_{y}$ 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 $\stackrel{P\vec}{p}p\ensuremath{\rightarrow}{{pp}}_{s\phantom{\rule{0.16em}{0ex}}}{\ensuremath{\pi}}^{0}$ 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 ${A}_{x,z}$.

The $pp\ensuremath{\rightarrow}pp{K}^{+}{K}^{\ensuremath{-}}$ reaction was measured below the $\ensuremath{\phi}$ threshold at a beam energy of 2.568 GeV using the COSY-ANKE magnetic spectrometer. By assuming that the four-body phase space is distorted only by the product of two-body final-state interactions, fits to a variety of one-dimensional distributions permit the evaluation of differential and total cross sections. The shapes of the distributions in the $Kp$ and $Kpp$ invariant masses are reproduced only if the ${K}^{\ensuremath{-}}p$ interaction is even stronger than that found at higher energy. The cusp effect in the ${K}^{+}{K}^{\ensuremath{-}}$ distribution at the ${K}^{0}{\overline{K}}^{0}$ threshold is much more clear and some evidence is also found for coupling between the ${K}^{\ensuremath{-}}p$ and ${\overline{K}}^{0}n$ channels. However, the energy dependence of the total cross section cannot be reproduced by considering only a simple product of such pairwise final-state interactions.

Measurements of the pd{yields}p{sub sp}dK{sup +}K{sup -} reaction, where p{sub sp} is a spectator proton, have been undertaken at the Cooler Synchrotron COSY-Juelich by detecting a fast deuteron in coincidence with a K{sup +}K{sup -} pair in the ANKE facility. Although the proton beam energy was fixed, the moving target neutron allowed values of the nonresonant quasifree pn{yields}dK{sup +}K{sup -} total cross section to be deduced up to an excess energy {epsilon}{approx_equal}100 MeV. Evidence is found for the effects of K{sup -}d and KK final state interactions. The comparison of these data with those of pp{yields}ppK{sup +}K{sup -} and pp{yields}dK{sup +}K{sup 0} shows that all the total cross sections are very similar in magnitude.

The pp ! ppreaction has been studied at the Cooler Synchrotron COSY-Julich, using the internal beam and ANKE facility. Total cross sections have been determined at three excess energiesnear the production threshold. The differential cross section closest to threshold at � � 18:5 MeV exhibits a clear S wave dominance as well as a noticeable effect due to the proton-proton final-state interaction. Taken together with data for pp! production, a significant enhancement of the �=! ratio of a factor 8 is found compared to predictions based on the Okubo-Zweig-Iizuka rule.

A measurement of the analyzing power A(y) of the p-->d--> (p p) + n reaction was carried out at the ANKE spectrometer at COSY at beam energies of 0.5 and 0.8 GeV by detection of a fast forward proton pair of small excitation energy E(pp) < 3 MeV. The S-wave dominance in the fast diproton is experimentally demonstrated in this reaction. While at T(p) = 0.8 GeV the measured analyzing power almost vanishes, it rises to nearly unity at T(p) = 0.5 GeV for neutrons emitted at theta(c.m.)(n) = 167 degrees. The results are compared with a model taking into account one-nucleon exchange, single scattering, and Delta(1232) excitation in the intermediate state. The model describes fairly well the unpolarized cross section obtained earlier and the analyzing power at 0.8 GeV; it fails to reproduce A(y) at 0.5 GeV.