Search for narrow NN-decoupled resonances in the πNN-system — an overview

The status of the search for NN-decoupled resonances in the πNN-system is reviewed. After a short survey on the history of dibaryon searches reactions suitable for detecting such resonances are discussed. Special emphasis is put on the pionic double charge exchange, where recently evidence for the signature of a narrow πNN resonance, called d‧, with I( J^P) = even (0 ^-) and m = 2.06 GeV has been quoted. Further reactions discussed in this context are the pion photoproduction on the deuteron and the two-pion production in nucleon-nucleon collisions.