Sign ambiguity in the KΣ channel

Ambiguities of the signs of N -> Sigma K coupling constants are studied in a multichannel partial wave analysis of a large body of pion- and photo-induced reactions. It is shown that the signs are not free from some ambiguities, and further experimental data are needed. Data on the reactions pi(+)p -> Sigma K-+(+) and gamma p -> K+Sigma(0) define rather well the isospin 3/2 contributions to these channels. However the lack of information on polarization observables for the reactions pi(-)p -> Sigma K-0(0), pi(-)p -> Sigma K--(+) and gamma p -> K-0 Sigma(+) does not allow us to fix uniquely the signs of N -> Sigma K coupling constants. As a consequence, also the contributions of nucleon resonances to these channels remain uncertain.