Exotic baryon resonances and the model of chiral solitons

A recently observed baryonic resonance with positive strangeness is discussed. The state is exotic because valence quarks alone cannot produce it and at least one quark–antiquark pair must be involved. The mass of the resonance is in agreement with chiral soliton models, which predict a number of other exotic states with different quantum numbers. Some of these states (e.g., those with strangeness $S=-2$ and charges $Q=0,-2$) are probably already being observed experimentally.