Low-lying JP = 12− resonances from chiral unitary dynamics

The s-wave meson-baryon interaction is studied using the lowest-order chiral lagrangian in a unitary coupled-channels Bethe-Salpeter equation. The resonances belonging to the low-lying JP = 12− octet, the N(1535), Λ(1620) and Ξ(1620), together with the Λ(1405) singlet, are generated dynamically through multiple meson-baryon scattering. The Λ(1405) appears as a mixture of K̄N and πΣ quasibond states, while the Λ(1670) is a KΞ quasibond state. Arguments are given to assigne JP = 12− to the unmeasured spin and parity of the Ξ(1620).