What is a pentaquark?
A pentaquark is any particle composed of five quarks and antiquarks – usually four quarks and one antiquark.
Pentaquarks do not occur naturally anywhere on Earth. For many years, they were merely hypothetical particles [1], but in the mid 2010s, they were confirmed to have been created at the Large Hadron Collider [2].
Pentaquarks can have many different compositions, but the first one to be confirmed was made of two up quarks, one down quark, one charm quark, and one charm antiquark: \(uudc\bar{c}\).
Pentaquarks are very short-lived particles, and can only be created in high-energy collisions. They may occur naturally in the universe in stellar cores, supernovæ, and stellar remnants such as neutron stars.
Names for other particles made of quarks
| Name | Number of Quarks | Status |
|---|---|---|
| diquark | 2 | confirmed – most mesons are diquarks |
| triquark | 3 | confirmed – most baryons are triquarks |
| tetraquark | 4 | confirmed |
| pentaquark | 5 | confirmed |
| hexaquark | 6 | hypothetical |
| heptaquark | 7 | hypothetical |
| octoquark | 8 | hypothetical |
| enneaquark | 9 | hypothetical |
| decaquark | 10 | hypothetical |
References
- ^ Observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner, Large Hadron Collider Beauty Experiment. https://lhcb-outreach.web.cern.ch/2022/07/05/observation-of-a-strange-pentaquark-a-doubly-charged-tetraquark-and-its-neutral-partner/
- ^ LHCb experiment discovers a new pentaquark, CERN. https://home.cern/news/news/physics/lhcb-experiment-discovers-new-pentaquark