Charmed baryons

Charmed baryons are a category of composite particles comprising all baryons with at least one unit of charm (quantum number). In quark model terms, charmed baryons consist of three quarks, one or more of which is a charm quark. These particles were first observed in the 1970s; since then, a large number of distinct charmed bayron states have been identified. In 2002, the SELEX collaboration, based at Fermilab published evidence of a doubly charmed baryon, but this claim has yet to be confirmed by another experiment.

History

The first charmed baryon to be discovered was the Λ⁺c. It is not entirely clear when the particle was first observed; there were a number of experiments which published evidence for the state beginning in 1975, but the reported masses were frequently lower than the real value. Since then, Λ⁺c have been produced and studied at many experiments, notably fixed-target experiments (such as FOCUS and SELEX) and e⁺e^- B-factories (ARGUS, CLEO, BABAR, BELLE).