We make a systematic test of soft-meson-theorem predictions for both elastic and inelastic pseudoscalar-meson-baryon threshold scattering amplitudes. The predictions are obtained by using an extrapolation procedure developed by Fubini and Furlan and by ourselves. Our results give considerable support to a theory of $\mathrm{SU}\left(3\right)\mathrm{}\times \mathrm{SU}\left(3\right)\mathrm{}$ symmetry breaking proposed recently by Gell-Mann, Oakes, and Renner, and imply that, in the absence of symmetry breaking, the mass of the $J^p={\frac{1}{2}}^{+}$ baryon octet would be approximately that of the physical nucleon.

• Received 2 October 1969

DOI:https://doi.org/10.1103/PhysRevD.1.151