Effective K̄N interaction based on chiral SU(3) dynamics

The effective K̄N interaction based on chiral SU(3) coupled-channel dynamics is derived and its extrapolation below the K̄N threshold is studied in detail. Starting from the coupled-channel scattering equations, we eliminate the channels other than K̄N and obtain an effective interaction in the single K̄N channel. An equivalent local potential in coordinate space is constructed such as to reproduce the full scattering amplitude of the chiral SU(3) coupled-channel framework. We discuss several realistic chiral SU(3)-based models in comparison to reach conclusions about the uncertainties involved. It turns out that, in the region relevant to the discussion of deeply bound K̄-nuclear few-body systems, the resulting energy-dependent, equivalent local potential is substantially less attractive than the one suggested in previous purely phenomenological treatments.