Microscopic description of η-nuclear systems

Investigations of η-few-nucleon systems dynamics in different processes at low energies were performed. The η-deuteron system was treated on the basis of the exact few-body Alt-Grassberger-Sandhas equations, the Faddeev-type coupling of these equations guarantees uniqueness of their solution. The scattering results (energy dependence of the ηd phase-shift and the total cross section for five different values of parameter Re αηN) are shown. The photoproduction of η-mesons on deuteron (γ + d → η + d) was also calculated and the results revealed very strong final state interactions. An analysis on the possibility of η-meson binding in the 3H, 3He, 4He systems within the framework of the Finite-rank-approximation of the nuclear Hamiltonian was performed. In all these calculations the Breit-Wigmer form of the ηnucleon T-matrix was used. It was found that in the region of ηN scattering length uncertainty resonances and quasibound states in the systems ηd , η3H, η3He, η4He are possible. 36 refs., 5 figs. (nevyjel) (author)