Three-body analysis of incoherent η\eta-photoproduction on the deuteron in the near threshold region

A three-body calculation of the reaction $\gamma d\to\eta np$ in the energy region from threshold up to 30 MeV above has been performed. The primary goal of this study is to assess the importance of the three-body aspects in the hadronic sector of this reaction. Results are presented for the $\eta$-meson spectrum as well as for the total cross section. The three-body results differ significantly from those predicted by a simple rescattering model in which only first-order $\eta N$- and $NN$-interactions in the final state are considered. The major features of the experimental data are well reproduced although right at threshold the rather large total cross section could not be explained.Comment: 6 pages revtex including 3 figure

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.</p