PIN PARTIAL WAVES AT LOW ENERGIES AND IN UNPHYSICAL REGION

The real parts of the πN partial wave amplitudes fl±(-) have been calculated from fixed-t dispersion relations, using phase shifts up to 2 GeV and the reggeized p-exchange model at higher energies. The comparison with Re fl±(-) as calculated directly from phase shifts shows to what extent the input is consistent with the fixed-t relation. The result is also of interest for the test of simple models, in particular for the comparison with predictions from current algebra. - A new evaluation of the partial wave dispersion relation for f0+(-) is presented. Combined with the first method it shows that the determination of the p-coupling parameter is based on an assumption which is difficult to justify. © 1969 Springer-Verlag.