# Baryon spectroscopy

Abstract : About 120 baryons and baryon resonances are known, from the abundant nucleon with $u$ and $d$ light-quark constituents up to the recently discovered $\Omega_b^-=bss$, and the $\Xi_b^-=bsd$ which contains one quark of each generation. In spite of this impressively large number of states, the underlying mechanisms leading to the excitation spectrum are not yet understood. Heavy-quark baryons suffer from a lack of known spin-parities. In the light-quark sector, quark-model calculations have met with considerable success in explaining the low-mass excitations spectrum but some important aspects like the mass degeneracy of positive-parity and negative-parity baryon excitations are not yet satisfactorily understood. At high masses, above 1.8 GeV, quark models predict a very high density of resonances per mass interval which is not observed. In this review, issues are identified discriminating between different views of the resonance spectrum; prospects are discussed how open questions in baryon spectroscopy may find answers from photo- and electro-production experiments which are presently carried out in various laboratories.
Document type :
Journal articles

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Submitted on : Thursday, January 15, 2009 - 8:44:23 AM
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### Citation

E. Klempt, J.-M. Richard. Baryon spectroscopy. Reviews of Modern Physics, American Physical Society, 2010, 82, pp.1095-1153. ⟨10.1103/RevModPhys.82.1095⟩. ⟨in2p3-00353229⟩

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