  The meson-baryon interactions in s-wave in the strangeness S=-1 sector are
studied using a chiral unitarity approach based on the next-to-leading order
chiral SU(3) Lagrangian. The model is fitted to the large set of experimental
data in different two-body channels. Particular attention is paid to the $\Xi$
hyperon production reaction, $\bar{K} N \rightarrow K \Xi$, where the effect of
the next-to-leading order terms in the Lagrangian play a crucial role, since
the cross section of this reaction at tree level is zero.
