Theoretical ambiguities of πN scattering amplitudes and isotopic invariance

Limitations on the ambiguities of πN-scattering amplitudes, imposed by the assumption of isotopic invariance, are studied. Continuous transformations without any limitations on the form of the amplitude are considered. A unified analysis of all the ambiguities is performed. The approach presented is of a sufficient generality to study the limitations imposed by the unitarity condition. Isotopic invariance complemented by the measurements of the polarized and total cross sections in elastic and charge exchange channels is shown to result in substantial limitations on ambiguities of πN amplitudes