In particle physics, exotic baryons are a type of hadron (bound states of quarks and gluons) with half-integer spin, but with a quark content different from the three quarks (qqq) present in conventional baryons. An example would be pentaquarks, consisting of four quarks and one antiquark (qqqqq̅).
So far, the only observed exotic baryons are the pentaquarks Pc(4380)+, Pc(4450)+ discovered in 2015,[1]Pc(4312)+ in 2019[2] and PΛ ψs(4338)0 in 2022 by the LHCb collaboration.[3]
Several types of exotic baryons that require physics beyond the Standard Model have been conjectured in order to explain specific experimental anomalies. There is no independent experimental evidence for any of these particles. One example is supersymmetricR-baryons,[4] which are bound states of 3 quarks and a gluino. The lightest R-baryon is denoted as S0 and consists of an up quark, a down quark, a strange quark and a gluino. This particle is expected to be long lived or stable and has been invoked to explain ultra-high-energy cosmic rays.[5][6] Stable exotic baryons are also candidates for strongly interacting dark matter.
It has been speculated by futurologistRay Kurzweil that by the end of the 21st century it might be possible by using femtotechnology to create new chemical elements composed of exotic baryons that would eventually constitute a new periodic table of elements in which the elements would have completely different properties than the regular chemical elements.[7]
