Lambda baryon
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In particle physics, Lambda (Λ) baryons are baryons containing an up quark, a down quark, and a third quark, either a strange quark (Λ0), a charm quark (Λ+c) or a bottom quark (Λ0b). The first Lambda particle discovered (Λ0) was discovered in 1947 during a study of cosmic ray interactions. Though the particle was expected to live 10-23 seconds, it actually survived for 10-10 seconds. The property which caused it to live so long was dubbed strangeness, and led to the discovery of the strange quark. Furthermore, these discoveries led to a principle known as the conservation of strangeness, wherein lightweight particles do not decay as quickly if they exhibit strangeness (due to the fact that non-weak methods of particle decay must preserve the strangeness of the decaying baryon). The Lambda particle Λ0 decays into a proton and a negative pion or a neutron and a neutral pion.
Contents |
[edit] List of Lambda baryons
| Particle | Symbol | Makeup | Rest mass MeV/c² |
Isospin I |
Spin(Parity) JP |
Q | S | C | B | Mean lifetime s |
Decays to |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Lambda [1] | Λ0 | uds | 1 115.683(6) | 0 | 1⁄2+ | 0 | −1 | 0 | 0 | 2.6×10−10 [2] | p+ + π− or n0 + π0 |
| charmed Lambda [3] | Λ+c | udc | 2 286.46(14) | 0 | 1⁄2+ | +1 | 0 | +1 | 0 | 2±0.6×10−13 | See Λ+c Decay Modes |
| bottom Lambda [4] | Λ0b | udb | 5 620.2±1.6 | 0 | 1⁄2+ | 0 | 0 | 0 | −1 | 1.409+0.55−0.54×10−12 | See Λ0b Decay Modes |
[edit] In popular culture
- The LGBT group at the Stanford Linear Accelerator Center named themselves the Lambda Particles.
[edit] See also
- Delta baryon
- List of particles
- Nucleon
- Omega baryon
- Particle Physics
- Physics portal
- Quark model
- Standard model
- Sigma baryon
- Timeline of particle discoveries
- Xi baryon
[edit] References
- ^ Particle Data Groups: 2006 Review of Particle Physics - Lambda. Retrieved on 2008-04-20.
- ^ Physics Particle Overview - Baryons. Retrieved on 2008-04-20.
- ^ Particle Data Groups: 2006 Review of Particle Physics - Charmed Lambda. Retrieved on 2008-04-20.
- ^ Particle Data Groups: 2006 Review of Particle Physics - Bottom Lambda0. Retrieved on 2008-04-20.
- The Lambda Baryon
- The European Physical Journal C, Review of Particle Physics, 1998
