Lambda particle
In particle physics, the Lambda particle is any one of a number of baryons containing an up quark, a down quark, and a third quark such as that the resulting particle exhibits a state of bottomness, strangeness, or is charmed. The first Lambda particle, consisting of an up, down, and strange quark, 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). Lambda particles decay into proton and negative pion or neutron and neutral pion.
| Particle | Symbol | Makeup | Rest mass MeV/c2 |
Spin | S | C | B | Mean lifetime s |
Decays to |
|---|---|---|---|---|---|---|---|---|---|
| Lambda | Λ0 | uds | 1115.7 | 1/2 | -1 | 0 | 0 | 2.60×10-10 | π- + p or πo + n |
| charmed Lambda | Λ+c | udc | 2285 | 1/2 | 0 | +1 | 0 | 2.0×10-13 | |
| bottom Lambda | Λ0b | udb | 5624 | 1/2 | 0 | 0 | -1 | 1.2×10-12 |
References
| Particles in physics | |
|---|---|
| Elementary particles | Fermions:
Quarks: u · d ·
s · c · b ·
t • Leptons: e- · e+ · μ- ·
μ+ · τ- · τ+ · νe · νμ · ντ Bosons: Gauge bosons: γ · g · W± · Z0 Other: Ghosts |
| Composite particles | Hadrons: Baryons(list)/Hyperons/Nucleons:
p · n · Δ ·
Λ · Σ · Ξ ·
Ω · Ξb • Mesons(list)/Quarkonia:
π · K · ρ · J/ψ · Υ Other: Atomic nuclei • Atoms • Exotic atoms: Positronium • Molecules |
| Hypothetical elementary particles | Superpartners: Axino · Dilatino ·
Chargino · Gluino · Gravitino · Higgsino · Neutralino ·
Sfermion · Slepton · Squark Other: Axion · Dilaton · Goldstone boson · Graviton · Higgs boson · Tachyon · X · Y · W' · Z' |
| Hypothetical composite particles | Exotic
hadrons: Exotic baryons: Other: Mesonic molecule |
| Quasiparticles | Davydov soliton · Exciton · Magnon · Phonon · Plasmon · Polariton · Polaron |
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