Omega baryons (often called simply Omega particles) are a family of subatomic hadrons which are represented by the symbol
Ω
and are either charge neutral or have a +2, +1 or −1 elementary charge. Additionally, they contain no up or down quarks.[1] Omega baryons containing top quarks are also 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 necessary for the strong interactions required for Hadronization, the process by which hadrons form from quarks and gluons.
The first omega baryon was the
Ω−
, it was made of three strange quarks, and was discovered in 1964.[3] The discovery was a great triumph in the study of quarks, 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.