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Omega (O) baryons are baryons containing neither up nor down quarks of isospin I?=?0. The first Omega discovered was the O-, made of three strange quarks. 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 already been predicted. Besides the O-, a charmed Omega particle (O0c) was discovered, in which a strange quark is replaced by a charm quark. The O- decays only via the weak interaction and has therefore a relatively long lifetime.[1] Spin (J) and parity (P) values for unobserved baryons are predicted by the quark model.[2]
Omega baryons
Omega
| Particle |
Symbol |
Quark
content |
Rest mass
MeV/c2 |
JP |
Q |
S |
C |
B |
Mean lifetime
s |
Decays to |
| Omega[3] |
O- |
sss |
1672.45±29 |
3/2+ |
-1 |
-3 |
0 |
0 |
8.21±0.11×10-11 |
?0 + K- or
?0 + p- or
?- + p0
|
| Charmed Omega[4] |
O0c |
ssc |
2697.5±2.6 |
1/2+ |
0 |
-2 |
+1 |
0 |
6.9±1.2×10-14 |
See O0c Decay Modes |
| Bottom Omega |
O-b |
ssb |
|
1/2+ |
-1 |
-2 |
0 |
-1 |
|
|
| Double charmed Omega† |
O+cc |
scc |
|
1/2+ |
+1 |
-1 |
+2 |
0 |
|
|
| Charmed bottom Omega† |
O0cb |
scb |
|
1/2+ |
0 |
-1 |
-1 |
-1 |
|
|
| Double bottom Omega† |
O-bb |
sbb |
|
1/2+ |
-1 |
-1 |
0 |
-2 |
|
|
| Triple charmed Omega† |
O++ccc |
ccc |
|
3/2+ |
+2 |
0 |
+3 |
0 |
|
|
| Double charmed bottom Omega† |
O+ccb |
ccb |
|
1/2+ |
+1 |
0 |
+2 |
-1 |
|
|
| Charmed double bottom Omega† |
O0cbb |
cbb |
|
1/2+ |
0 |
0 |
+1 |
-2 |
|
|
| Triple bottom Omega† |
O-bbb |
bbb |
|
3/2+ |
-1 |
0 |
0 |
-3 |
|
|
† Particle (or quantity, i.e. spin) has neither been observed nor indicated.
Recent discoveries
The Ob particle is a "doubly-strange" baryon containing two strange quarks and a bottom quark. It was first reported in September 2008 by physicists working on the DZero experiment experiment at the Fermi National Accelerator Laboratory.[5] [6]
See also
References
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