%0 Journal Article
%T Update of the pi N --> eta N and eta N --> eta N partial-wave amplitudes
%A Mijo Batinic
%A Ivan Dadic
%A Ivo Slaus
%A Alfred Svarc
%A B. M. K. Nefkens
%A T. -S. H. Lee
%J Physics
%D 1997
%I arXiv
%X A three-channel, multi-resonance, unitary model developed in 1995 is used to determine the $\pi N \rightarrow \eta N$ and $\eta N \rightarrow \eta N$ amplitudes using as input the latest data for the dominant $S_{11}$ $\pi N$ elastic scattering partial wave following suggestions of Prof. G. H\"{o}hler. The sign error in the numerical evaluation of the dispersion integral in the original publication is eliminated. The remaining weighted data set for the $\pi N \rightarrow \eta N$ total and differential cross sections is used as in the original publication. The correction of the numerical error influences the $\eta N$ cusp effect and improves the quality of the fit to the input data. However, our new result for the $\eta N$ scattering length, $a_{\eta N }= (0.717 \pm 0.030) + i (0.263 \pm 0.025)$ fm, is a sole consequence of the correction of the $S_{11}$ input and suggests that the $\eta d$ system is unbound or loosely bound.
%U http://arxiv.org/abs/nucl-th/9703023v1