Bound states, resonances and poles in the low-energy K-barN

The locations in the complex energy plane of the dynamic poles of the T matrix for the (K-bar N,Σπ) system are calculated. Investigated are a quark bag model and several potential models, including one which agrees with the strong interaction shift in kaonic hydrogen as well as scattering data. The parameters of the model are fit to K-p scattering and reaction cross sections, branching ratios, and mass spectra from K-p→ Σπππ, Λπππ. The ΣP1322(1385) and ΛD03(1520) resonances are found to be predominately elementary bag states with considerable dressing for the ΣP13. The ΛS01(1405) appears as a complicated composite systems arising from two poles. The model with certain parameter sets does predict two sign changes in the real part of the K-bar N scattering amplitude near threshold, but they are not quite at the correct energies to produce agreement with the sign of the strong interaction shift of kaonic hydrogen. (author). 10 refs., 10 figs