Updated study of S-wave K¯N scattering and related spectroscopy at NLO UChPT

The meson-baryon scattering with strangeness −1 is studied within the coupled-channel unitary chiral perturbation theory. A large amount of experimental data are analyzed. This strongly constrains the free parameters in our calculation and also the resulting meson-baryon scattering amplitudes. Several different strategies to perform the fits to data are discussed, which allows one to make the important check on the stability of the results obtained. Our final threshold parameters for K¯N scattering and baryon resonance properties are stable and confident.