KN scattering and the problem of the S=+-1 baryon resonances

The present situation on low energy KN scattering is reviewed. The phenomenological knowledge of low energy KN scattering has improved, with the large amount of new data on the Ksub(L)sup(0)p→Ksub(S)sup(0)p channel in particular. Correspondingly the number of acceptable phase shift solutions has decreased in number. Nevertheless there still is no answer on the problem of the existence of exotic resonances. The I=1 structure at 1.25 GeV/c seems to be explained as due to the opening up of the KΔ channel, which in its turn is due to a superposition of waves. The I=0 structure at 1.15 GeV/c may have a similar explanation in connection with opening up of the K*N channel, but here the information is more scanty. The best candidate for an exotic state remains the I=0 structure at 0.8 GeV/c. All analyses agree that the interaction is strongly attractive. The phase shift solution is either of the C or D type, or something in between