We study the meson-baryon interaction in S-wave in the strangeness S=-1
sector using a chiral unitary approach based on a next-to-leading order chiral
SU(3) Lagrangian. We fit our model to the large set of experimental data in
different two-body channels. We pay particular attention to the KˉN→KΞ reaction, where the effect of the next-to-leading order
terms in the Lagrangian are sufficiently large to be observed, since at tree
level the cross section of this reaction is zero. For these channels we improve
our approach by phenomenologically taking into account effects of the high spin
hyperonic resonances.Comment: 8 pages, 4 figures, presented at the II Russian-Spanish Congress
"Particle and Nuclear Physics at all Scales and Cosmology", Saint-Petersburg,
October 1-4, 2013. arXiv admin note: text overlap with arXiv:1311.5025; and
with arXiv:hep-ph/0505239 by other author