Experimental evidence for an exotic baryon first came in 2003 from the observation of a S = +1 narrow resonance 1 at 1540± 10 MeV which can be associated with an exotic pentaquark state with content uudds̄. Confirmation came quickly from a series of experiments, with the observation of sharp peaks 2,3,4,5 in the nK and pK S invariant mass spectrum near 1540 MeV, in each case with a width limited...

The measured masses of the three charge states of the charmed Σc baryon are found to be in disagreement with a sum rule based on the quark model, but relying on no detailed assumptions about the form of the interaction. This poses a significant problem for the charmed baryon sector of the quark model. Other relations among charmed baryon masses are also discussed. PACS numbers: 12.40.Yx., 14.20...