"Omega particle" redirects here. For usage of the term in Star Trek, see The Omega Directive.
Not to be confused with Omega meson.
Bubble chamber trace of the first observed Ω baryon event at Brookhaven National Laboratory, adapted from original tracing. The tracks of neutral particles (dashed lines) are not visible in the bubble chamber. The collision of a K− meson with a proton creates an Ω−, a K0 and a K+. The Ω− decays into a π− and a Ξ0, which in turn decays into a Λ0 and a π0. The Λ0 decays into a proton and a π−. The π0, invisible due to its short lifetime, decays into two photons (γ), which in turn each create an electron-positron pair.
The omega baryons are a family of subatomic hadron (a baryon) particles that are represented by the symbol Ω and are either neutral or have a +2, +1 or −1 elementary charge. They are baryons containing no up or down quarks.[1] Omega baryons containing top quarks are not expected to be observed. This is because the Standard Model predicts the mean lifetime of top quarks to be roughly 5×10−25 s,[2] which is about a twentieth of the timescale for strong interactions, and therefore that they do not form hadrons.
The first omega baryon discovered was the Ω− , made of three strange quarks, in 1964.[3] The discovery was a great triumph in the study of quark processes, since it was found only after its existence, mass, and decay products had been predicted in 1961 by the American physicist Murray Gell-Mann and, independently, by the Israeli physicist Yuval Ne'eman. Besides the Ω− , a charmed omega particle ( Ω0 c) was discovered in 1985, in which a strange quark is replaced by a charm quark. The Ω− decays only via the weak interaction and has therefore a relatively long lifetime.[4] Spin (J) and parity (P) values for unobserved baryons are predicted by the quark model.[5]
Since omega baryons do not have any up or down quarks, they all have isospin 0.
^Particle Data Group. "2010 Review of Particle Physics – Naming scheme for hadrons" (PDF). Retrieved 26 December 2011.
^
A. Quadt (2006). "Top quark physics at hadron colliders". European Physical Journal C. 48 (3): 835–1000. Bibcode:2006EPJC...48..835Q. doi:10.1140/epjc/s2006-02631-6. S2CID 121887478.
^
V. E. Barnes; et al. (1964). "Observation of a Hyperon with Strangeness Minus Three" (PDF). Physical Review Letters. 12 (8): 204. Bibcode:1964PhRvL..12..204B. doi:10.1103/PhysRevLett.12.204. OSTI 12491965.
^
R. Nave. "The Omega baryon". HyperPhysics. Retrieved 26 November 2009.
^Körner, J.G; Krämer, M; Pirjol, D (1 January 1994). "Heavy baryons". Progress in Particle and Nuclear Physics. 33: 787–868. arXiv:hep-ph/9406359. Bibcode:1994PrPNP..33..787K. doi:10.1016/0146-6410(94)90053-1. S2CID 118931787.
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