Sigma baryon
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Sigma particles are baryons composed two up and down quarks, arranged in an isospin 1 state. When the sigma baryon's flavour is unspecified, it usually refers to a strange sigma. Bottom sigmas have recently been observed.
Strange sigmas are hyperons, but charmed and bottom sigmas are not.
| Particle | Symbol | Makeup | Rest mass MeV/c² |
Isospin I |
Spin(Parity) JP |
Q | S | C | B | Mean lifetime s |
Decays to |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Sigma [1] | Σ+ | uus | 1 189.37(0.7) | 1 | 1⁄2+ | +1 | −1 | 0 | 0 | 8.18±0.26×10−11 | p+ + π0 or n0 + π+ |
| Sigma [2] | Σ0 | uds | 1 192.642(24) | 1 | 1⁄2+ | 0 | −1 | 0 | 0 | 7.4±0.7×10−20 | Λ0 + γ |
| Sigma [3] | Σ− | dds | 1 197.449(30) | 1 | 1⁄2+ | −1 | −1 | 0 | 0 | 1.479±0.11×10−10 | n0 + π− |
| Sigma resonance [4] | Σ+(1385) | uus | 1 382.8(4) | 1 | 3⁄2+ | +1 | −1 | 0 | 0 | Λ + π or Σ + π |
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| Sigma resonance [4] | Σ0(1385) | uds | 1 383.7±1.0 | 1 | 3⁄2+ | 0 | −1 | 0 | 0 | Λ + π or Σ + π |
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| Sigma resonance [4] | Σ−(1385) | dds | 1 387.2(5) | 1 | 3⁄2+ | −1 | −1 | 0 | 0 | Λ + π or Σ + π |
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| charmed Sigma [5] | Σ++c(2455) | uuc | 2 454.02(18) | 1 | 1⁄2+ | +2 | 0 | +1 | 0 | Λ+c + π+ | |
| charmed Sigma [5] | Σ+c(2455) | udc | 2 452.9(4) | 1 | 1⁄2+ | +1 | 0 | +1 | 0 | Λ+c + π0 | |
| charmed Sigma [5] | Σ0c(2455) | ddc | 2 453.76(18) | 1 | 1⁄2+ | 0 | 0 | +1 | 0 | Λ+c + π− | |
| bottom Sigma [6] | Σ+b | uub | 5,807.8+3.7−3.9 | 1 | 1⁄2+ | +1 | 0 | 0 | −1 | Λb + π+ | |
| bottom Sigma† | Σ0b | udb | 1 | 1⁄2+ | 0 | 0 | 0 | −1 | |||
| bottom Sigma [6] | Σ−b | ddb | 5 815.2±2.7 | 1 | 1⁄2+ | −1 | 0 | 0 | −1 | Λb + π− | |
| bottom Sigma resonance [6] | Σ∗+b(5830?) | uub | 5,829+3.3−3.6 | 1 | 3⁄2+ | +1 | 0 | 0 | −1 | ||
| bottom Sigma resonance† | Σ∗0b(?) | udb | 1 | 3⁄2+ | 0 | 0 | 0 | −1 | |||
| bottom Sigma resonance [6] | Σ∗−b(5830?) | ddb | 5,836.4+3.8−3.7 | 1 | 3⁄2+ | −1 | 0 | 0 | −1 |
† Particle currently unobserved, but predicted by the standard model.
[edit] See also
- Delta baryon
- Hyperon
- Lambda baryon
- List of mesons
- List of particles
- Nucleon
- Omega baryon
- Physics portal
- Timeline of particle discoveries
- Xi baryon
[edit] References
- ^ Particle Data Groups: 2006 Review of Particle Physics - Sigma+. Retrieved on 2008-04-20.
- ^ Particle Data Groups: 2006 Review of Particle Physics - Sigma0. Retrieved on 2008-04-20.
- ^ Particle Data Groups: 2006 Review of Particle Physics - Sigma-. Retrieved on 2008-04-20.
- ^ a b c Particle Data Groups: 2006 Review of Particle Physics - Sigma(1385). Retrieved on 2008-04-20.
- ^ a b c Particle Data Groups: 2006 Review of Particle Physics - Charmed Sigma(2455). Retrieved on 2008-04-20.
- ^ a b c d First Observation of Heavy Baryons Σ+b and Σ∗+b. Retrieved on 2008-04-20.
- Particle Data Group: W.-M. Yao et al., J. Phys G 33, 1 (2006).
- The Sigma Baryon. HyperPhysics.
- "CDF finds exotic relatives of protons and neutrons". Fermilab Today. 2006-10-23
- Particle Data Group - Sigma Baryons (2005)
