Fixed poles in the t-channel helicity-flip amplitude in charge- and hypercharge-exchange reactions

Abstract

We try to find evidence for fixed poles in two-body meson-baryon scattering. The contribution of wrong-signature fixed poles occur in wrong-signature sum rules. We evaluate the first wrong-signature sum rule for the t-channel helicity flip amplitude in π N, KN charge-exchange and in hypercharge-exchange scatterings. According to recent theoretical analysis the J = 0 KN charge-exchange wrong-signature fixed pole is generated, via t-channel unitarity, from the πN one. Its existence implies a J = 0 KN charge-exchange right-signature fixed pole. Evidence for the existence of a J = 0 wrong-signature fixed pole is found in all of them. It is also found that the non-peripheral resonances are mainly responsible for all these fixed poles.