Dynamical Basis forη-Baryon Interactions

The recent experimental evidence for a rapid rise in $\eta$ production near threshold in the reactions ${\pi }^{-}+p\to {\eta }^0+n$ and $K^{-}+p\to {\eta }^0+\Lambda$ is analyzed on the basis of a constant-$K$-matrix formalism. Representative scattering lengths for the $\eta$-baryon systems are introduced to illustrate pertinent features of the presently known experimental data. A dynamical basis for the physical situation is discussed in terms of possible new baryon states due to virtual or bound states of the $\eta$-baryon systems. Comparison of the results with expectations from a conjectured $\eta$ octet of baryon (½-) states for $\mathrm{SU}\left(3\right)\mathrm{}$ symmetry is briefly referred to.