Energies and residues of the nucleon resonances N(1535) and N(1650)

Abstract

We extract pole positions for the N(1535) and N(1650) resonances using two different models. The positions are determined from fits to different subsets of the existing pi N --> pi N, pi N --> eta N, and gamma p --> eta p data and found to be 1510(10)-i85(15)MeV and 1660(10)-i70(10)MeV, when the data is described in terms of two poles. Sensitivity to the choice of fitted data is explored. The corresponding pi pi and eta eta residues of these poles are also extracted. [S0556-2813(98)07612-2].