On quasi-bound states in eta-nucleys systems
  The optical potential for the $\eta$-meson is calculated. This is based on a new determination of a large $\eta$-N scattering length and recent experiments of $\eta$ production in two nucleon collisions. These determine the $\eta$ - nuclear potential well to be about 45 MeV deep and able to support S, P, D and F quasibound states. Some of the higher angular momentum states are fairly narrow and offer a chance of experimental detection. 
J.Kulpa, S.Wycech (Soltan Institute for Nuclear Studies), A.M. Green   (Helsinki Institute of Physics)