New Interpretation of theπN→πNScattering Data and the Charge-Independence Hypothesis

The isospin dependence and the charge independence of the $\pi N\to \pi N$ differential cross sections is studied by a graphical method reported previously. An interesting and not well-known observation is made, namely, that for the non-spin-flip and the spin-flip cross section separately the triangular inequalities are accurately satisfied as equalities at low energies (below 200 MeV), and in backward scattering also at higher energies. This observation, which is believed to be of a fundamental nature, does not have a trivial explanation in the usual formalism. A suggestion is made as to how the formalism could be modified so that the observation would have a simple interpretation as a new kind of unitarity condition.