Chiral SU(3) theory of antikaon–nucleon interactions with improved threshold constraints

image-nucleon interactions are investigated in the framework of coupled-channels dynamics based on the next-to-leading order chiral SU(3) meson–baryon effective Lagrangian. A recent determination of the 1s shift and width of kaonic hydrogen enables us to set accurate constraints on the coupled-channels meson–baryon amplitudes in the strangeness image sector. Theoretical uncertainties in the subthreshold extrapolation of the coupled-channels amplitudes are discussed. Using this framework, we give predictions for image-neutron interactions and for the spectrum of the image resonance. A simplified, effective three-channel model using leading order chiral SU(3) meson–baryon interactions is also constructed for convenient application in image-nuclear few-body calculations.