Effective K̄N interaction with strong πΣ dynamics constrained by chiral SU(3) symmetry

We derive a single-channel effective K̄N interaction from chiral SU(3) coupledchannel dynamics, emphasizing the important role of the πΣ channel and the structure of the Λ(1405) resonance. The chiral low energy theorem requires strongly attractive interaction not only in the K̄N channel but also in the πΣ channel. As a consequence of the strong πΣ dynamics, the equivalent potential in single K̄N channel turns out to be less attractive than the one used in a purely phenomenological approach.