Studies of Di‐proton production at ANKE

The study of NN‐interactions with production of $1S0$ proton pairs (diprotons) provides a new approach to hadron interactions at intermediate energies. The use of the polarised COSY beams and the ANKE polarised internal target allows one to conduct single and double polarization experiments. A number of processes including $pd→{pp}sn,$ production of one and two pions in pN collisions, and the $pp→{pp}sγ$ process, have been investigated.

Information on the near‐threshold single pion production with formation of a diproton in the processes $pp→{pp}sπ0$ and $pn→{pp}sπ−$ is urgently needed for further development of chiral perturbation theory. The measurements of $dσ/dΩ, Ay$ and the spin‐correlation coefficients $Ax,x$ and $Ax,z$ will permit an amplitude analysis that should provide a non‐trivial test of the χPT predictions. A combined study of these processes will lead to the isolation of the strength parameter d of the four‐nucleon‐pion contact interaction in χPT. Preliminary ANKE results on $dσ/dΩ$ and $Ay$ in these processes are presented, and the future experimental programme is discussed.