Pentaquarks

摘要

I discuss the recent experimental and theoretical developments following the discovery of the Θ~+ pentaquark - an exotic uudds baryon resonance observed by several experiments, and Ξ~(*--)(ddssu) reported by NA49. I focus on the theoretical interpretation of the data, on the predictions for related exotic states, and on several unresolved questions: Why some experiments observe the pentaquarks and others do not, the apparently extremely narrow width of the Θ~+, and the determination of its parity. I also discuss the proposed heavy-quark pentaquarks - Θ_c (uuddc) and Θ_b~+ (uuddb), which are expected to be extremely narrow or even stable against strong decays. H1 recently reported the observation of a possible Θ_c candidate in D~(*-)p channel. Pentaquarks are also being searched for in e~+e~- and γγ in the LEP data and at B-factories.