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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.

Lambda particles
Particle Symbol Makeup Rest mass
Spin S C B Mean lifetime
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


  • The Lambda Baryon
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Lambda_particle". A list of authors is available in Wikipedia.
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