Representation Mixing andSU3Symmetry Breaking in the½−Baryon Octet

Widths and coupling-constant products are obtained for members of the ${\mathrm{½}}^{-}$ baryon resonance octet by fitting the $\eta$-production data near threshold with a direct-channel resonance model. An interpretation of the fitted parameters in terms of representation mixing is shown to lead to large singlet-octet and decuplet-octet mixing. Quark-model modifications of the vertices, as proposed by Mitra and Ross, are also considered, with much the same results. An alternative interpretation in terms of an $S{U}_3$ symmetry-breaking interaction based on a suggestion by Pakvasa is given.