π−pcharge-exchange amplitude zeros from a Barrelet analysis between 1.4 and 2.3 GeV

Using the available scattering and polarization pion-nucleon charge-exchange data, we have performed a Barrelet-moment analysis between 1.4 and 2.3 GeV. The method allows us to identify and discard data with important systematic error. Above 1.5 GeV, ten zeros are unambiguously required in order to represent the retained data. An attempt is made to resolve the discrete ambiguity and to obtain the location of amplitude zeros close to the physical region.